MD Licensing Exam — Questions and Answers

Question 1: A 65-year-old male with a long-standing history of type 2 diabetes and hypertension presents with fatigue, lower extremity edema, and a metallic taste in his mouth. Laboratory results show a GFR of 25 mL/min/1.73 m², serum potassium of 5.8 mEq/L, and BUN of 80 mg/dL. Which of the following medications that acts on the renal system is most likely contributing to his hyperkalemia?

Lisinopril (Correct answer)
Hydrochlorothiazide
Furosemide
Amlodipine

Correct answer: Lisinopril

Lisinopril, an ACE inhibitor, is a common cause of hyperkalemia in patients with chronic kidney disease (CKD). ACE inhibitors block the conversion of angiotensin I to angiotensin II, leading to decreased aldosterone secretion. Aldosterone is responsible for potassium excretion in the distal tubules, so its inhibition leads to potassium retention. Furosemide (a loop diuretic) and hydrochlorothiazide (a thiazide diuretic) both increase potassium excretion. Amlodipine, a calcium channel blocker, does not significantly affect potassium levels.

Question 2: A 60-year-old woman presents with progressive dysphagia to solids then liquids, weight loss, and regurgitation of undigested food. Barium swallow shows a 'bird's beak' tapering. What is the diagnosis?

Achalasia (Correct answer)
Esophageal carcinoma
Diffuse esophageal spasm
Zenker's diverticulum

Correct answer: Achalasia

Achalasia is characterized by failure of the lower esophageal sphincter to relax and loss of peristalsis, producing the classic bird's beak appearance on barium swallow.

Question 3: Which enzyme converts angiotensin I to angiotensin II and is inhibited by ACE inhibitors?

Aldosterone synthase
Angiotensin-converting enzyme (Correct answer)
Neprilysin
Renin

Correct answer: Angiotensin-converting enzyme

ACE (angiotensin-converting enzyme) cleaves angiotensin I to form the vasoactive angiotensin II, and ACE inhibitors block this step.

Question 4: A patient has hyponatremia, inappropriately concentrated urine (>100 mOsm/kg), and normal volume status with no edema or dehydration. Serum uric acid and BUN are low. What is the diagnosis?

SIADH (Correct answer)
Psychogenic polydipsia
Hypothyroidism
Cerebral salt wasting

Correct answer: SIADH

SIADH presents with euvolemic hyponatremia, concentrated urine despite low serum osmolality, and dilute serum markers (low BUN, uric acid) due to water retention.

Question 5: What does the combining form 'hepato-' refer to?

Spleen
Heart
Liver (Correct answer)
Lung

Correct answer: Liver

Hepato- derives from the Greek 'hepar' meaning liver.

Question 6: An 8-year-old child presents with pallor, jaundice, and splenomegaly. Peripheral smear shows spherocytes and reticulocytosis. The osmotic fragility test is positive. What is the inheritance pattern?

X-linked recessive
Autosomal dominant (Correct answer)
Autosomal recessive
Mitochondrial

Correct answer: Autosomal dominant

Hereditary spherocytosis is most commonly autosomal dominant (spectrin or ankyrin mutations), though autosomal recessive forms exist; autosomal dominant accounts for ~75% of cases.

Question 7: A 55-year-old woman presents with episodic right upper quadrant pain, nausea, and jaundice following fatty meals. Ultrasound shows gallstones. Which composition of gallstones is most common in the United States?

Pigment (brown) stones
Pigment (black) stones
Calcium bilirubinate stones
Cholesterol stones (Correct answer)

Correct answer: Cholesterol stones

Cholesterol gallstones account for approximately 80% of gallstones in the US and are associated with obesity, female sex, pregnancy, and rapid weight loss.

Question 8: An HIV-positive patient with CD4 count of 150 cells/μL develops ring-enhancing brain lesions on MRI with surrounding edema. Serology is positive for IgG antibodies. What is the most likely diagnosis and empiric treatment?

Progressive multifocal leukoencephalopathy; antiretrovirals
Cerebral toxoplasmosis; pyrimethamine + sulfadiazine (Correct answer)
Cryptococcal meningitis; fluconazole
CNS lymphoma; methotrexate

Correct answer: Cerebral toxoplasmosis; pyrimethamine + sulfadiazine

Multiple ring-enhancing lesions in an HIV patient with positive Toxoplasma IgG should be treated empirically with pyrimethamine + sulfadiazine (+ leucovorin); response within 2 weeks confirms diagnosis.

Question 9: On peripheral smear, teardrop cells (dacrocytes), nucleated RBCs, and immature granulocytes are seen together. This leukoerythroblastic picture is classic for:

G6PD hemolysis
Megaloblastic anemia
Autoimmune hemolytic anemia
Myelophthisic anemia / myelofibrosis (Correct answer)

Correct answer: Myelophthisic anemia / myelofibrosis

Myelofibrosis or bone marrow infiltration (myelophthisis) causes a leukoerythroblastic smear with teardrop cells as RBCs are squeezed through fibrotic marrow.

Question 10: A 7-year-old boy presents with a palpable purpuric rash on his lower extremities, arthralgia, and abdominal pain. A urinalysis reveals microscopic hematuria and proteinuria. These findings are most consistent with which of the following conditions?

Post-streptococcal Glomerulonephritis
Alport Syndrome
Henoch-Schönlein Purpura (HSP) Nephritis (Correct answer)
Minimal Change Disease

Correct answer: Henoch-Schönlein Purpura (HSP) Nephritis

The clinical triad of a palpable purpuric rash (without thrombocytopenia), arthritis, and abdominal pain is characteristic of Henoch-Schönlein Purpura (HSP), an IgA-mediated small-vessel vasculitis. Renal involvement (HSP Nephritis) is common, occurring in up to 50% of patients, and typically manifests as hematuria and proteinuria due to glomerular inflammation.

Question 11: A 70-year-old man presents with urinary frequency, hesitancy, and a post-void residual of 200 mL. Digital rectal exam shows a smooth, enlarged prostate. PSA is 2.8 ng/mL. What is the most likely diagnosis?

Bladder cancer
Prostate cancer
Prostatitis
Benign prostatic hyperplasia (Correct answer)

Correct answer: Benign prostatic hyperplasia

BPH causes obstructive lower urinary tract symptoms with a smooth, uniformly enlarged prostate and elevated post-void residual without PSA dramatically elevated.

Question 12: A 55-year-old woman is newly diagnosed with Pulmonary Arterial Hypertension (PAH), classified as low-to-intermediate risk. She has no significant comorbidities. According to current treatment guidelines, what is the recommended initial therapeutic strategy?

Monotherapy with a calcium channel blocker.
Monotherapy with an endothelin receptor antagonist (ERA).
Immediate referral for lung transplantation evaluation.
Initial combination therapy with an ERA and a PDE-5 inhibitor. (Correct answer)

Correct answer: Initial combination therapy with an ERA and a PDE-5 inhibitor.

Current guidelines from bodies like the ESC/ERS recommend initial oral combination therapy for most newly diagnosed PAH patients who are not at high risk. The most common initial combination is an endothelin receptor antagonist (ERA) and a phosphodiesterase-5 (PDE-5) inhibitor. Monotherapy is generally reserved for specific situations, and calcium channel blocker monotherapy is only appropriate for the small subset of patients who show a positive response to acute vasoreactivity testing. Immediate transplant referral is reserved for high-risk patients.

Question 13: A 45-year-old with HIV (CD4 count 85 cells/μL) presents with progressive dyspnea, dry cough, and bilateral ground-glass opacities. LDH is elevated. What is the first-line treatment?

Fluconazole
Ganciclovir
Trimethoprim-sulfamethoxazole plus prednisone (Correct answer)
Liposomal amphotericin B

Correct answer: Trimethoprim-sulfamethoxazole plus prednisone

TMP-SMX is first-line for Pneumocystis jirovecii pneumonia (PCP), and adjunctive corticosteroids are indicated when PaO2 <70 mmHg or A-a gradient >35 mmHg.

Question 14: A 70-year-old presents with acute painless monocular vision loss described as a curtain falling over the eye, lasting 10 minutes then resolving. What does this represent?

Retinal detachment
Angle-closure glaucoma
Amaurosis fugax (transient monocular blindness) (Correct answer)
Migraine with visual aura

Correct answer: Amaurosis fugax (transient monocular blindness)

Amaurosis fugax is transient monocular blindness caused by embolic occlusion of the ophthalmic artery and is a TIA equivalent requiring urgent workup.

Question 15: Which pulmonary function pattern is most consistent with a diagnosis of hypersensitivity pneumonitis?

Obstructive pattern with air trapping
Restrictive pattern with reduced DLCO (Correct answer)
Normal spirometry with elevated TLC
Mixed obstructive-restrictive with normal DLCO

Correct answer: Restrictive pattern with reduced DLCO

Hypersensitivity pneumonitis typically produces a restrictive pattern with reduced DLCO due to interstitial inflammation and fibrosis.

Question 16: Free water clearance (CH2O) is negative in a patient. What does this indicate?

Patient has diabetes insipidus
Patient is excreting dilute urine relative to plasma
Patient's GFR is below normal
Patient is excreting concentrated urine and retaining free water (Correct answer)

Correct answer: Patient is excreting concentrated urine and retaining free water

Negative free water clearance means the kidney is excreting urine more concentrated than plasma, retaining free water (as in SIADH or normal ADH response to dehydration).

Question 17: A 22-year-old male is brought to the emergency department after being found unconscious at a rave. He is diagnosed with rhabdomyolysis secondary to MDMA (ecstasy) use. Which of the following is the primary mechanism by which rhabdomyolysis causes acute kidney injury (AKI)?

Renal tubular obstruction by myoglobin casts and direct cytotoxicity of myoglobin. (Correct answer)
Severe dehydration leading to prerenal azotemia.
Direct nephrotoxic effect of the drug on the glomeruli.
Immune-mediated glomerulonephritis triggered by muscle breakdown products.

Correct answer: Renal tubular obstruction by myoglobin casts and direct cytotoxicity of myoglobin.

In rhabdomyolysis, massive breakdown of skeletal muscle releases large amounts of myoglobin into the circulation. This myoglobin is filtered by the glomeruli but can precipitate in the renal tubules, especially in the setting of dehydration and acidic urine, forming casts that cause physical obstruction. Additionally, the heme component of myoglobin is directly toxic to renal tubular epithelial cells, causing acute tubular necrosis.

Question 18: A patient with ulcerative colitis limited to the rectum is best described as having which subtype?

Pancolitis
Proctitis (Correct answer)
Left-sided colitis
Ileocolitis

Correct answer: Proctitis

Proctitis refers to ulcerative colitis confined to the rectum, the most distal and mildest form of the disease.

Question 19: A 55-year-old presents with ipsilateral Horner syndrome, contralateral pain/temperature loss, ipsilateral facial numbness, dysphagia, and hoarseness. Which artery is occluded?

Middle cerebral artery
Anterior spinal artery
Posterior inferior cerebellar artery (Correct answer)
Basilar artery

Correct answer: Posterior inferior cerebellar artery

Lateral medullary (Wallenberg) syndrome results from PICA occlusion and presents with the described crossed sensory deficit and cranial nerve findings.

Question 20: Which demyelinating disease is characterized by optic neuritis, transverse myelitis, and area postrema syndrome, with seropositivity for AQP4-IgG?

Neuromyelitis optica spectrum disorder (Correct answer)
Clinically isolated syndrome
Acute disseminated encephalomyelitis
Multiple sclerosis

Correct answer: Neuromyelitis optica spectrum disorder

AQP4-IgG (anti-aquaporin-4) antibodies are the hallmark of neuromyelitis optica spectrum disorder (NMOSD).

Question 21: A 60-year-old with known lung cancer presents with confusion, proximal weakness, and serum sodium of 118 mEq/L. Urine sodium is elevated and urine osmolality is high. What is the mechanism?

Cerebral salt wasting
Nephrogenic diabetes insipidus
Syndrome of inappropriate ADH secretion (SIADH) (Correct answer)
Adrenal insufficiency

Correct answer: Syndrome of inappropriate ADH secretion (SIADH)

SIADH from ectopic ADH production by small cell lung cancer causes dilutional hyponatremia with inappropriately elevated urine osmolality and sodium.

Question 22: A newborn fails to pass meconium within 48 hours of birth. Rectal biopsy shows absence of ganglion cells in the submucosal and myenteric plexuses. What is the diagnosis?

Meconium ileus
Imperforate anus
Hirschsprung disease (Correct answer)
Intussusception

Correct answer: Hirschsprung disease

Hirschsprung disease is caused by failure of neural crest cell migration, resulting in an aganglionic segment of colon that cannot relax.

Question 23: A 35-year-old woman with known MEN1 has recurrent peptic ulcers refractory to PPIs and fasting hypergastrinemia. What additional tumor should be sought?

Insulinoma
Gastrinoma (Zollinger-Ellison syndrome) (Correct answer)
VIPoma
Glucagonoma

Correct answer: Gastrinoma (Zollinger-Ellison syndrome)

Gastrinoma causing Zollinger-Ellison syndrome is associated with MEN1 and presents with hypergastrinemia and refractory peptic ulcers.

Question 24: A 40-year-old male nonsmoker presents with lower lobe-predominant emphysema detected on CT. Serum AAT level is 45 mg/dL (normal >100). What is the most appropriate specific treatment?

High-dose vitamin E supplementation
Intravenous alpha-1 antitrypsin augmentation therapy (Correct answer)
Lung volume reduction surgery
Prophylactic azithromycin

Correct answer: Intravenous alpha-1 antitrypsin augmentation therapy

IV AAT augmentation therapy is specifically indicated for patients with severe alpha-1 antitrypsin deficiency (Pi*ZZ genotype) and established airflow obstruction.

Question 25: Which finding on high-resolution CT (HRCT) chest is most characteristic of usual interstitial pneumonia (UIP) pattern?

Bilateral subpleural honeycombing with traction bronchiectasis (Correct answer)
Ground-glass opacities in upper lobes
Crazy-paving pattern
Perilymphatic nodules

Correct answer: Bilateral subpleural honeycombing with traction bronchiectasis

UIP pattern on HRCT shows bilateral, subpleural, basal-predominant honeycombing with or without traction bronchiectasis, representing the radiologic correlate of IPF.

Question 26: Which ion channel abnormality is most responsible for the triggered arrhythmias seen in digoxin toxicity?

Sodium-potassium ATPase inhibition causing intracellular calcium overload (Correct answer)
L-type calcium channel activation
HCN channel hyperpolarization shift
Potassium channel blockade prolonging repolarization

Correct answer: Sodium-potassium ATPase inhibition causing intracellular calcium overload

Digoxin inhibits Na⁺/K⁺-ATPase, raising intracellular Na⁺, which reduces Na⁺/Ca²⁺ exchanger activity, leading to calcium overload and delayed afterdepolarizations.

Question 27: A 55-year-old man undergoes cardiac catheterization after a large anterior STEMI. Which coronary artery territory is most likely occluded?

Posterior descending artery (PDA)
Left anterior descending artery (LAD) (Correct answer)
Right coronary artery (RCA)
Left circumflex artery (LCX)

Correct answer: Left anterior descending artery (LAD)

The LAD supplies the anterior wall, apex, and anterior interventricular septum, making it the vessel most responsible for anterior ST-elevation myocardial infarction.

Question 28: Ectopic pregnancy most commonly implants in which location?

Abdominal cavity
Cervix
Ovary
Fallopian tube ampulla (Correct answer)

Correct answer: Fallopian tube ampulla

Approximately 95% of ectopic pregnancies occur in the fallopian tube, with the ampullary segment (70%) being the most common implantation site.

Question 29: A 38-year-old presents with recurrent spontaneous pneumothorax. CT shows bilateral cystic lung disease. She has a history of renal angiomyolipomas. What is the most likely diagnosis?

Langerhans cell histiocytosis
Lymphangioleiomyomatosis (LAM) (Correct answer)
Birt-Hogg-Dubé syndrome
Lymphoid interstitial pneumonia

Correct answer: Lymphangioleiomyomatosis (LAM)

Lymphangioleiomyomatosis presents in women of childbearing age with bilateral thin-walled pulmonary cysts, spontaneous pneumothorax, and renal angiomyolipomas.

Question 30: A patient develops bloody diarrhea after eating undercooked hamburger at a barbecue. Stool culture grows E. coli that does not ferment sorbitol. Which toxin is most responsible for hemolytic uremic syndrome in this setting?

Heat-labile toxin
Heat-stable toxin
Cholera toxin
Shiga toxin (Correct answer)

Correct answer: Shiga toxin

E. coli O157:H7 produces Shiga toxin (Stx1/Stx2) which damages renal endothelium, leading to hemolytic uremic syndrome characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury.

Question 31: Preeclampsia is defined as new-onset hypertension (≥140/90 mmHg) after 20 weeks gestation with:

Elevated serum hCG
Facial edema and headache
Proteinuria or end-organ damage (Correct answer)
Fetal growth restriction only

Correct answer: Proteinuria or end-organ damage

Preeclampsia is defined as new-onset hypertension of ≥140/90 mmHg after 20 weeks with either significant proteinuria (≥300 mg/24h) or end-organ dysfunction.

Question 32: A 35-year-old develops a painful vesicular rash in a dermatomal distribution on the left thorax that does not cross the midline. Which antiviral reduces duration and severity if started within 72 hours of rash onset?

Foscarnet
Ribavirin
Ganciclovir
Acyclovir or valacyclovir (Correct answer)

Correct answer: Acyclovir or valacyclovir

Herpes zoster (VZV reactivation) manifests as a painful dermatomal vesicular rash; oral acyclovir or valacyclovir initiated within 72 hours reduces duration, severity, and risk of postherpetic neuralgia.

Question 33: A 50-year-old presents with rapidly progressive dementia, myoclonus, and periodic sharp wave complexes on EEG. CSF 14-3-3 protein is elevated. MRI shows cortical ribboning on DWI. What is the diagnosis?

Anti-NMDA receptor encephalitis
Viral encephalitis
Hashimoto encephalopathy
Creutzfeldt-Jakob disease (Correct answer)

Correct answer: Creutzfeldt-Jakob disease

Rapidly progressive dementia with myoclonus, periodic EEG complexes, CSF 14-3-3, and DWI cortical ribboning is classic for Creutzfeldt-Jakob disease.

Question 34: Which antibiotic is first-line treatment for uncomplicated cellulitis in a non-penicillin-allergic patient?

Vancomycin
Cephalexin (Correct answer)
Doxycycline
Clindamycin

Correct answer: Cephalexin

Cephalexin (a first-generation cephalosporin) is first-line oral therapy for uncomplicated cellulitis caused by streptococci and methicillin-susceptible staphylococci.

Question 35: A 52-year-old male is diagnosed with a duodenal ulcer, and a urease breath test is positive for Helicobacter pylori. He has no known drug allergies. According to the most recent ACG (American College of Gastroenterology) guidelines, which of the following is a recommended first-line treatment regimen?

Esomeprazole and ranitidine for 8 weeks.
Omeprazole, clarithromycin, and metronidazole for 7 days.
Bismuth subsalicylate, metronidazole, tetracycline, and a PPI for 14 days. (Correct answer)
A proton pump inhibitor (PPI) and amoxicillin for 10 days.

Correct answer: Bismuth subsalicylate, metronidazole, tetracycline, and a PPI for 14 days.

Recent ACG guidelines recommend bismuth quadruple therapy (a PPI, bismuth, metronidazole, and tetracycline for 14 days) as a preferred first-line treatment for H. pylori, largely due to rising clarithromycin resistance. Clarithromycin-based triple therapy is no longer recommended as a primary empiric option in many regions. A PPI and amoxicillin alone is insufficient for eradication. A PPI with an H2 blocker will heal the ulcer but not treat the underlying H. pylori infection.

Question 36: A 55-year-old woman is receiving combination chemotherapy for breast cancer. Which of the following agents is most notoriously associated with a dose-dependent, cumulative cardiotoxicity that can lead to congestive heart failure?

Vincristine
Methotrexate
Cisplatin
Doxorubicin (Correct answer)

Correct answer: Doxorubicin

Doxorubicin, an anthracycline antibiotic, is well-known for causing dose-dependent cardiotoxicity. The risk of developing cardiomyopathy and congestive heart failure increases significantly with higher cumulative doses. Vincristine is associated with peripheral neuropathy, Cisplatin with nephrotoxicity and ototoxicity, and Methotrexate with myelosuppression and mucositis.

Question 37: A 50-year-old man undergoes total gastrectomy for gastric cancer. Which nutritional deficiency will he inevitably develop without supplementation?

Folate deficiency
Vitamin D deficiency
Iron deficiency anemia only
Vitamin B12 deficiency (Correct answer)

Correct answer: Vitamin B12 deficiency

Total gastrectomy eliminates production of intrinsic factor by parietal cells, making it impossible to absorb vitamin B12 via the ileal receptor, necessitating parenteral supplementation.

Question 38: Which mechanism best describes how selective serotonin reuptake inhibitors (SSRIs) exert their antidepressant effect?

Block postsynaptic 5-HT2A receptors to reduce serotonin side effects
Irreversibly inhibit monoamine oxidase enzymes A and B
Inhibit the serotonin transporter at the presynaptic terminal, increasing synaptic serotonin concentration (Correct answer)
Block presynaptic alpha-2 receptors to increase norepinephrine and serotonin release

Correct answer: Inhibit the serotonin transporter at the presynaptic terminal, increasing synaptic serotonin concentration

SSRIs selectively inhibit the serotonin transporter (SERT) at the presynaptic terminal, preventing serotonin reuptake and thereby increasing serotonin concentration in the synaptic cleft.

Question 39: A 45-year-old woman presents with weight gain, fatigue, and constipation. Labs show TSH 12 mIU/L and free T4 0.6 ng/dL. Which finding would most likely also be present?

Hypercalcemia
Elevated free T3
Hypokalemia
Elevated LDL cholesterol (Correct answer)

Correct answer: Elevated LDL cholesterol

Hypothyroidism impairs LDL receptor expression, leading to elevated LDL cholesterol and dyslipidemia.

Question 40: Standard intrapartum prophylaxis against Group B Streptococcus (GBS) neonatal disease uses:

IV ampicillin (Correct answer)
IV vancomycin
IV azithromycin
Oral clindamycin

Correct answer: IV ampicillin

Intravenous penicillin G or ampicillin is the standard intrapartum prophylaxis for GBS-colonized mothers to prevent neonatal early-onset GBS disease.

Question 41: A 75-year-old woman was recently diagnosed with polymyalgia rheumatica (PMR). During a follow-up visit, she reports developing a new, unilateral headache over her right temple and jaw claudication when chewing. Which of the following conditions is most likely associated with her PMR and new symptoms?

Fibromyalgia
Cervical spondylosis
Trigeminal neuralgia
Giant Cell Arteritis (GCA) (Correct answer)

Correct answer: Giant Cell Arteritis (GCA)

Polymyalgia rheumatica and Giant Cell Arteritis are closely related inflammatory conditions. Approximately 50% of patients with GCA also have PMR, and about 15-20% of patients with PMR will develop GCA. The new onset of headache, jaw claudication, and temporal tenderness in an elderly patient with PMR is highly suspicious for GCA, a vasculitis that can lead to irreversible blindness if not promptly treated with high-dose corticosteroids.

Question 42: The Nikolsky sign (skin separation with lateral pressure) is positive in which condition?

Contact dermatitis
Pemphigus vulgaris (Correct answer)
Psoriasis
Lichen planus

Correct answer: Pemphigus vulgaris

The Nikolsky sign is positive in pemphigus vulgaris due to loss of intraepidermal adhesion from autoantibodies against desmoglein.

Question 43: A 16-year-old boy has tall stature, arachnodactyly, lens dislocation upward, and an aortic root diameter of 4.8 cm. Mutation in which gene is responsible?

FBN1 (fibrillin-1) (Correct answer)
COL1A1 (type I collagen)
ELN (elastin)
ACTA2 (smooth muscle actin)

Correct answer: FBN1 (fibrillin-1)

Marfan syndrome is caused by mutations in FBN1 encoding fibrillin-1, disrupting microfibrils and TGF-β signaling, affecting connective tissue in multiple organ systems.

Question 44: What does the prefix 'ante-' mean?

Before (Correct answer)
Against
Beside
After

Correct answer: Before

Ante- means before or in front of, as in antepartum (before delivery).

Question 45: A 55-year-old woman with known cirrhosis presents with confusion, asterixis, and elevated ammonia. What precipitant should be ruled out first?

Hyperglycemia
Gastrointestinal bleeding (Correct answer)
Pulmonary embolism
Hyponatremia

Correct answer: Gastrointestinal bleeding

GI bleeding is a common precipitant of hepatic encephalopathy because blood protein in the gut is metabolized by bacteria to ammonia, worsening encephalopathy.

Question 46: A 35-year-old patient with a known history of HIV, non-adherent to antiretroviral therapy, presents with a new-onset seizure. His CD4 count is 48 cells/µL. A contrast-enhanced MRI of the brain reveals multiple ring-enhancing lesions, primarily located in the basal ganglia. What is the most likely diagnosis?

Primary CNS lymphoma
Progressive Multifocal Leukoencephalopathy (PML)
Cryptococcoma
Cerebral Toxoplasmosis (Correct answer)

Correct answer: Cerebral Toxoplasmosis

In an HIV-positive patient with a CD4 count below 100 cells/µL, the presence of multiple ring-enhancing brain lesions, particularly in the basal ganglia, is highly characteristic of cerebral toxoplasmosis, caused by the reactivation of latent Toxoplasma gondii infection. [26, 27, 38] While primary CNS lymphoma is a key differential, it more commonly presents as a single lesion. Given the classic presentation, empiric treatment for toxoplasmosis is typically initiated. [29]

Question 47: First-line topical treatment for scabies in adults is:

Lindane 1% lotion
Permethrin 5% cream (Correct answer)
Benzyl benzoate 25%
Ivermectin oral

Correct answer: Permethrin 5% cream

Permethrin 5% cream applied to the entire body and left on overnight is the first-line treatment for scabies in adults and children over 2 months.

Question 48: A patient with chronic kidney disease has a GFR of 20 mL/min. Which acid-base disorder is most expected?

Hyperchloremic normal anion gap acidosis
High anion gap metabolic acidosis (Correct answer)
Metabolic alkalosis
Respiratory alkalosis

Correct answer: High anion gap metabolic acidosis

Chronic kidney disease causes accumulation of unmeasured anions (sulfate, phosphate, organic acids) leading to high anion gap metabolic acidosis.

Question 49: A 70-year-old man with diabetes and CKD stage 3 has an HbA1c of 9.2%. His provider avoids aggressive glycemic targets. What is the primary reason for setting a less stringent HbA1c goal (e.g., <8%)?

Reduced cardiovascular benefit in elderly
Reduced need for monitoring in CKD
Increased risk of hypoglycemia with limited ability to recognize or recover (Correct answer)
Lower cost of medications

Correct answer: Increased risk of hypoglycemia with limited ability to recognize or recover

Elderly patients with CKD have blunted hypoglycemia counterregulation and impaired drug clearance, making tight control dangerous with high hypoglycemia risk.

Question 50: The Bishop score is used clinically to assess:

Risk of gestational diabetes
Cervical favorability for labor induction (Correct answer)
Placental function and fetal well-being
Fetal lung maturity

Correct answer: Cervical favorability for labor induction

The Bishop score evaluates cervical dilation, effacement, station, consistency, and position to predict the likelihood of successful labor induction.

Question 51: The standard US screening approach for gestational diabetes at 24-28 weeks gestation is:

Two-step: 50g GCT then 100g OGTT if abnormal (Correct answer)
Fasting plasma glucose alone
HbA1c measurement
Random plasma glucose

Correct answer: Two-step: 50g GCT then 100g OGTT if abnormal

The two-step approach — a 1-hour 50g glucose challenge test followed by a 3-hour 100g OGTT if the screen is positive — is the standard US method for GDM screening.

Question 52: Which pathophysiologic change most directly causes the elevated BNP levels in patients with decompensated heart failure?

Hepatic congestion reducing BNP metabolism
Renal failure impairing BNP clearance
Sympathetic activation stimulating BNP gene transcription
Myocardial wall stress from increased ventricular filling pressure stretching cardiomyocytes (Correct answer)

Correct answer: Myocardial wall stress from increased ventricular filling pressure stretching cardiomyocytes

Elevated ventricular wall stress from high filling pressures mechanically stretches cardiomyocytes, triggering cleavage of proBNP into BNP and NT-proBNP.

Question 53: Long QT syndrome predisposes to torsades de pointes. Which underlying mechanism is common to both congenital and acquired forms?

Reduced repolarizing current (IKr) prolonging phase 3 of the action potential (Correct answer)
Increased sodium influx shortening the action potential plateau
Enhanced calcium release from the sarcoplasmic reticulum
Increased automaticity in Purkinje fibers

Correct answer: Reduced repolarizing current (IKr) prolonging phase 3 of the action potential

Both congenital LQTS (e.g., KCNQ1, HERG mutations) and drug-induced forms reduce the rapid delayed rectifier potassium current (IKr), prolonging repolarization and QT interval.

Question 54: A 45-year-old presents with fatigue, splenomegaly, and a WBC of 120,000/μL with a left shift. Cytogenetics reveals t(9;22). Which kinase is constitutively activated in this condition?

JAK2
FLT3
BCR-ABL1 (Correct answer)
KIT

Correct answer: BCR-ABL1

The Philadelphia chromosome t(9;22) creates the BCR-ABL1 fusion gene, producing a constitutively active tyrosine kinase that drives CML.

Question 55: A patient on broad-spectrum antibiotics develops profuse watery diarrhea. Stool toxin assay is positive for toxin B. Which antibiotic is first-line treatment?

Metronidazole (IV)
Vancomycin (oral) (Correct answer)
Ciprofloxacin
Rifaximin

Correct answer: Vancomycin (oral)

For non-severe Clostridioides difficile infection, oral vancomycin (or fidaxomicin) is now preferred over metronidazole per current IDSA guidelines due to superior cure rates.

Question 56: HELLP syndrome is characterized by which triad of findings?

Hemolysis, Elevated Liver enzymes, Low Platelets (Correct answer)
Hyperglycemia, Elevated lipids, Low albumin
Hypertension, Edema, Low protein
High hematocrit, Elevated LDH, Low potassium

Correct answer: Hemolysis, Elevated Liver enzymes, Low Platelets

HELLP syndrome is defined by Hemolysis (microangiopathic), Elevated Liver enzymes, and Low Platelets (<100,000/μL) — a life-threatening complication of preeclampsia.

Question 57: A newborn presents with ambiguous genitalia, vomiting, and hyponatremia with hyperkalemia. 17-hydroxyprogesterone is markedly elevated. What enzyme is deficient?

21-hydroxylase (Correct answer)
17-alpha hydroxylase
3-beta hydroxysteroid dehydrogenase
11-beta hydroxylase

Correct answer: 21-hydroxylase

21-hydroxylase deficiency is the most common cause of congenital adrenal hyperplasia, blocking cortisol and aldosterone synthesis with excess 17-OHP accumulation.

Question 58: Which finding on lumbar puncture is most characteristic of bacterial meningitis compared to viral meningitis?

Clear CSF with mildly elevated protein
Lymphocytic pleocytosis with normal glucose
Elevated protein with neutrophilic pleocytosis and low glucose (Correct answer)
Xanthochromia with RBCs

Correct answer: Elevated protein with neutrophilic pleocytosis and low glucose

Bacterial meningitis classically shows neutrophilic pleocytosis, markedly elevated protein, and low glucose due to bacterial consumption and disrupted transport.

Question 59: A newborn is found to have bilateral renal agenesis, oligohydramnios, pulmonary hypoplasia, and limb deformities. What syndrome is this?

VACTERL association
Alport syndrome
Potter sequence (Correct answer)
Prune belly syndrome

Correct answer: Potter sequence

Potter sequence results from bilateral renal agenesis causing oligohydramnios, which leads to compression deformities (limbs, face) and pulmonary hypoplasia from lack of fetal urination.

Question 60: A 55-year-old male presents with sudden-onset tearing chest pain radiating to the back. BP is 180/100 mmHg in the right arm and 150/90 mmHg in the left arm. What is the most likely diagnosis?

Esophageal rupture
Aortic dissection (Correct answer)
Acute MI
Pulmonary embolism

Correct answer: Aortic dissection

Aortic dissection classically presents with tearing chest pain radiating to the back and a blood pressure differential between arms due to involvement of subclavian artery origins.

Question 61: A 63-year-old woman with a major past medical history of breast cancer arrives at the hospital with a three-day history of a sore throat, lethargy, and a petechial rash throughout the anterior abdominal wall and both lower extremities. A white blood cell count of 115.5 cells/ul (normal: 3.5-10.5 cells/ul), of which 77% are blasts, a hemoglobin level of 6.1 g/dl (normal: 12–16 g/dl), and a platelet count of 22,000/ul (normal: 150–400 thousand/ul) are all revealed by laboratory tests. She receives induction therapy while being treated at the hospital. The following statement is true:

Prior treatment with doxorubicin (an anthracycline) for breast cancer has increased her risk of developing leukemia (Correct answer)
All of the above
Leukemias associated with prior chemotherapy are associated with an unfavorable prognosis (Correct answer)
Anthracyclines are associated with cardiomyopathy but are there is no association between their use and secondary leukemias

Correct answer: Prior treatment with doxorubicin (an anthracycline) for breast cancer has increased her risk of developing leukemia

The patient's history of breast cancer treated with doxorubicin (an anthracycline) is a significant risk factor for developing secondary acute myeloid leukemia (AML). Anthracyclines are known to be topoisomerase II inhibitors, which can cause DNA damage and lead to specific chromosomal translocations associated with therapy-related AML. This type of secondary leukemia often carries an unfavorable prognosis.

Question 62: A 58-year-old male is diagnosed with Chronic Myeloid Leukemia (CML). Cytogenetic analysis confirms the presence of the Philadelphia chromosome. Which of the following best describes the molecular abnormality and the corresponding class of targeted therapy used as first-line treatment?

JAK2 mutation; JAK inhibitors
B-Raf V600E mutation; BRAF inhibitors
FLT3 mutation; FLT3 inhibitors
BCR-ABL fusion gene; Tyrosine kinase inhibitors (Correct answer)

Correct answer: BCR-ABL fusion gene; Tyrosine kinase inhibitors

Chronic Myeloid Leukemia (CML) is characterized by the Philadelphia chromosome, which results from a translocation between chromosomes 9 and 22. This creates the BCR-ABL fusion gene, which encodes a constitutively active tyrosine kinase, driving leukemogenesis. The mainstay of CML treatment is targeted therapy with tyrosine kinase inhibitors (TKIs), such as imatinib, which specifically block the activity of the BCR-ABL protein.

Question 63: A diabetic patient develops painful peripheral neuropathy. Tight glycemic control is initiated. Which additional medication has the best evidence for symptomatic relief of diabetic peripheral neuropathy?

Hydrocodone alone
NSAIDs
Gabapentin or pregabalin (Correct answer)
Methotrexate

Correct answer: Gabapentin or pregabalin

Gabapentin and pregabalin are FDA-approved and first-line agents for painful diabetic peripheral neuropathy, modulating calcium channel activity in sensory neurons.

Question 64: Which Pap smear result in a woman over 25 requires immediate colposcopy?

ASCUS with negative HPV co-test
Negative for intraepithelial lesion
LSIL with negative HPV
HSIL (high-grade squamous intraepithelial lesion) (Correct answer)

Correct answer: HSIL (high-grade squamous intraepithelial lesion)

HSIL on Pap smear requires immediate colposcopy with directed biopsy due to high risk of underlying CIN 2/3 or invasive cervical carcinoma.

Question 65: A 55-year-old woman is found to have a thyroid nodule. Fine-needle aspiration cytology shows 'follicular neoplasm' (Bethesda IV). What is the recommended next step?

Observation with annual ultrasound
Radioactive iodine ablation
Repeat FNA in 6 months
Diagnostic hemithyroidectomy (lobectomy) (Correct answer)

Correct answer: Diagnostic hemithyroidectomy (lobectomy)

Bethesda IV cytology cannot distinguish follicular adenoma from carcinoma on FNA; surgical lobectomy is required for definitive histologic diagnosis.

Question 66: A 2-year-old boy presents with colicky abdominal pain, vomiting, and currant jelly stools. Ultrasound shows a 'target sign' in the right upper quadrant. What is the diagnosis?

Intussusception (Correct answer)
Malrotation with volvulus
Hirschsprung disease
Meckel's diverticulum

Correct answer: Intussusception

Intussusception is the telescoping of one segment of bowel into another, classically presenting in children aged 6 months to 2 years with the triad of colicky pain, vomiting, and currant jelly stools.

Question 67: A patient develops severe abdominal pain, fever, and watery diarrhea 5 days after completing a course of clindamycin. Colonoscopy shows yellowish plaques on the colonic mucosa. What is the treatment of choice?

Metronidazole or vancomycin (oral) (Correct answer)
Ampicillin-sulbactam
Rifaximin
Ciprofloxacin

Correct answer: Metronidazole or vancomycin (oral)

Clostridioides difficile colitis (pseudomembranous colitis) is treated with oral metronidazole for mild-moderate disease or oral vancomycin for severe disease, with fidaxomicin as an alternative.

Question 68: A 40-year-old returns from sub-Saharan Africa with fever, painless facial swelling, and a rapidly moving subconjunctival worm. Which organism causes this?

Wuchereria bancrofti
Loa loa (Correct answer)
Onchocerca volvulus
Dracunculus medinensis

Correct answer: Loa loa

Loa loa (African eye worm) is transmitted by Chrysops flies and characteristically migrates across the conjunctiva, causing transient Calabar swellings; it is endemic to West and Central Africa.

Question 69: A 48-year-old with rheumatoid arthritis develops a new pleural effusion. Pleural fluid analysis shows glucose of 18 mg/dL, pH 7.00, LDH 2,100 U/L, and protein 4.8 g/dL. What is the most likely etiology?

Chylothorax
Parapneumonic empyema
Rheumatoid pleuritis (Correct answer)
Malignant effusion

Correct answer: Rheumatoid pleuritis

Rheumatoid pleural effusions characteristically show very low glucose (<30 mg/dL), very low pH, and very high LDH due to immune complex deposition and impaired glucose transport.

Question 70: A 48-year-old man with a history of alcohol abuse presents with severe epigastric pain radiating to the back. His serum lipase is markedly elevated. On day two of admission, he develops a respiratory rate of 24/min, a heart rate of 110 bpm, and his BUN increases from 18 to 30 mg/dL. Which of the following is the best indicator of a severe disease course in this patient?

The presence of epigastric tenderness on exam.
The degree of lipase elevation.
The etiology being alcohol-related.
The development of Systemic Inflammatory Response Syndrome (SIRS). (Correct answer)

Correct answer: The development of Systemic Inflammatory Response Syndrome (SIRS).

The development and persistence of Systemic Inflammatory Response Syndrome (SIRS) is a key predictor of severity and mortality in acute pancreatitis, as it often precedes organ failure. The patient's tachycardia, tachypnea, and rising BUN (indicating renal dysfunction) are signs of SIRS and organ dysfunction. The absolute level of lipase does not correlate with disease severity. While alcohol is a common cause, the etiology itself is not as strong a prognostic indicator as the patient's systemic response. Epigastric tenderness is an expected finding but does not predict severity.

Question 71: A 40-year-old man with heavy alcohol use abruptly stops drinking. On day 2, he develops tachycardia, hypertension, diaphoresis, tremor, and anxiety. What is the most serious potential complication if left untreated?

Korsakoff's psychosis
Wernicke's encephalopathy
Delirium tremens with tonic-clonic seizures (Correct answer)
Alcoholic hepatitis

Correct answer: Delirium tremens with tonic-clonic seizures

Delirium tremens is the most severe complication of alcohol withdrawal, typically occurring 48-96 hours after cessation and potentially life-threatening; benzodiazepines are the treatment of choice.

Question 72: Eclampsia differs from preeclampsia by the additional presence of:

Severe proteinuria (>5g/24h)
New-onset grand mal seizures (Correct answer)
Placental abruption
HELLP syndrome

Correct answer: New-onset grand mal seizures

Eclampsia is the occurrence of new-onset grand mal (generalized tonic-clonic) seizures in a woman with preeclampsia that cannot be attributed to other causes.

Question 73: A 65-year-old woman is brought to the emergency department from a nursing home with a suspected urinary tract infection. She is lethargic, her blood pressure is 85/45 mmHg despite a 1-liter crystalloid bolus, and her serum lactate is 5.0 mmol/L. According to the Surviving Sepsis Campaign's 'Hour-1 Bundle', which of the following is a critical and time-sensitive intervention that must be initiated immediately?

Placing a central venous catheter for CVP monitoring
Administering intravenous hydrocortisone
Initiating continuous renal replacement therapy
Obtaining blood cultures and administering broad-spectrum antibiotics (Correct answer)

Correct answer: Obtaining blood cultures and administering broad-spectrum antibiotics

The Surviving Sepsis Campaign 'Hour-1 Bundle' emphasizes several key interventions to be initiated immediately upon recognition of sepsis or septic shock. Among the highest priorities are obtaining blood cultures before starting antibiotics and then promptly administering broad-spectrum antibiotics, ideally within the first hour. [22, 23, 35] Early and appropriate antibiotic administration is one of the few interventions proven to reduce mortality in septic shock. [5, 8]

Question 74: A 40-year-old develops ascending flaccid paralysis starting in both legs 2 weeks after a GI illness with Campylobacter jejuni. CSF shows elevated protein with normal cell count (albuminocytologic dissociation). Which condition is this?

West Nile virus encephalitis
Transverse myelitis
Guillain-Barré syndrome (Correct answer)
Botulism

Correct answer: Guillain-Barré syndrome

Guillain-Barré syndrome is a post-infectious demyelinating polyneuropathy often triggered by C. jejuni due to molecular mimicry between gangliosides and bacterial lipooligosaccharide; CSF shows albuminocytologic dissociation.

Question 75: A 55-year-old pigeon handler develops progressive pneumonia with relative bradycardia (pulse-temperature dissociation), dry cough, and hyponatremia. CXR shows patchy infiltrates. Which organism causes this atypical pneumonia?

Mycoplasma pneumoniae
Legionella pneumophila (Correct answer)
Coxiella burnetii
Chlamydophila psittaci

Correct answer: Legionella pneumophila

Legionella pneumophila causes Legionnaires' disease, characterized by relative bradycardia, hyponatremia, diarrhea, and pontiac fever-like prodrome; it grows in water-cooling systems and causes lobar pneumonia.

Question 76: A 65-year-old smoker presents with proximal limb weakness that improves with repeated muscle use. Reflexes are absent but return after exercise. What antibody mediates this condition?

Anti-AChR
Anti-MuSK
Anti-voltage-gated calcium channel (VGCC) (Correct answer)
Anti-GQ1b

Correct answer: Anti-voltage-gated calcium channel (VGCC)

Lambert-Eaton myasthenic syndrome is caused by anti-VGCC antibodies that reduce presynaptic acetylcholine release, often paraneoplastic with SCLC.

Question 77: Lichen planus is classically described by the '6 P's.' Which set correctly identifies them?

Pale, Pigmented, Periungual, Pruritic, Papular, Palmar
Pruritic, Purple, Polygonal, Planar, Papules, Plaques (Correct answer)
Painful, Papular, Pink, Pruritic, Peripheral, Peeling
Pink, Pustular, Papillary, Perioral, Pruritic, Progressive

Correct answer: Pruritic, Purple, Polygonal, Planar, Papules, Plaques

Lichen planus is described by the 6 P's: Pruritic, Purple, Polygonal, Planar, Papules, and Plaques, often with Wickham's striae on the surface.

Question 78: A 40-year-old man with ankylosing spondylitis has failed NSAIDs. Which biologic class is most effective for his axial disease?

TNF-alpha inhibitors (e.g., adalimumab) (Correct answer)
IL-6 receptor antagonists (e.g., tocilizumab)
CTLA-4 Ig fusion proteins (e.g., abatacept)
B-cell depletion agents (e.g., rituximab)

Correct answer: TNF-alpha inhibitors (e.g., adalimumab)

TNF-alpha inhibitors are first-line biologics for ankylosing spondylitis refractory to NSAIDs; IL-17 inhibitors are an alternative, but IL-6 and rituximab show limited efficacy for axial disease.

Question 79: A 45-year-old man with psoriasis develops DIP joint involvement, nail pitting, and 'sausage digits.' Rheumatoid factor is negative. What pattern of psoriatic arthritis does he have?

Symmetric polyarthritis
Axial spondyloarthropathy
Arthritis mutilans
Distal interphalangeal joint predominant disease (Correct answer)

Correct answer: Distal interphalangeal joint predominant disease

DIP joint involvement with nail changes and dactylitis (sausage digits) is the classic distal pattern of psoriatic arthritis, which is seronegative.

Question 80: A patient with newly diagnosed hypothyroidism is started on levothyroxine. When should TSH be rechecked to assess adequacy of dosing?

After 4–6 weeks (Correct answer)
Only when symptoms recur
After 6 months
After 1 week

Correct answer: After 4–6 weeks

TSH has a half-life that requires 4–6 weeks for a new steady state to be reached after initiating or adjusting levothyroxine therapy.

Question 81: A patient with Graves' disease is started on methimazole. Which of the following best describes the primary mechanism of action of this thionamide medication?

It destroys thyroid follicular cells through radioactive emission.
It inhibits the thyroid peroxidase enzyme, blocking the organification of iodine. (Correct answer)
It blocks the peripheral conversion of T4 to T3.
It competitively blocks the TSH receptor on thyroid follicular cells.

Correct answer: It inhibits the thyroid peroxidase enzyme, blocking the organification of iodine.

Methimazole's primary mechanism of action is the inhibition of the thyroid peroxidase (TPO) enzyme. This enzyme is crucial for oxidizing iodide and coupling it to tyrosine residues on thyroglobulin (a process called organification), which is a critical step in the synthesis of thyroid hormones T3 and T4. Propylthiouracil (PTU) also inhibits TPO but has the additional effect of blocking the peripheral conversion of T4 to T3.

Question 82: The combining form 'dermo-' or 'dermato-' refers to:

Bone
Skin (Correct answer)
Nerve
Blood

Correct answer: Skin

Dermato- derives from Greek 'derma' meaning skin.

Question 83: A 25-year-old man with hemophilia A requires surgery. His factor VIII level is 2%. Which product replaces the deficient factor and is the treatment of choice?

Recombinant factor VIII concentrate (Correct answer)
Fresh frozen plasma
Cryoprecipitate
Desmopressin (DDAVP)

Correct answer: Recombinant factor VIII concentrate

Recombinant factor VIII concentrate is first-line for severe hemophilia A; DDAVP is only effective for mild hemophilia A (factor VIII >5%).

Question 84: A 35-year-old HIV-positive patient with a CD4 count of 50 cells/μL presents with headache and fever. CSF India ink preparation reveals encapsulated yeast. Which organism is responsible?

Candida albicans
Cryptococcus neoformans (Correct answer)
Aspergillus fumigatus
Histoplasma capsulatum

Correct answer: Cryptococcus neoformans

Cryptococcus neoformans causes meningitis in severely immunocompromised patients and is identified by India ink staining showing a large polysaccharide capsule.

Question 85: A 25-year-old presents with painless cervical lymphadenopathy and night sweats after a cat scratch. Warthin-Starry silver stain of a lymph node biopsy shows pleomorphic gram-negative rods. Which organism is responsible?

Pasteurella multocida
Yersinia pestis
Francisella tularensis
Bartonella henselae (Correct answer)

Correct answer: Bartonella henselae

Cat-scratch disease is caused by Bartonella henselae, transmitted by cat scratch or bite, producing regional lymphadenopathy; Warthin-Starry silver stain identifies the organisms in tissue.

Question 86: A 45-year-old man presents with episodic epigastric pain relieved by food and antacids. Upper endoscopy reveals a duodenal ulcer. Which organism is most likely responsible?

Helicobacter pylori (Correct answer)
Campylobacter jejuni
Escherichia coli
Clostridium difficile

Correct answer: Helicobacter pylori

Helicobacter pylori is responsible for approximately 90% of duodenal ulcers and disrupts the mucosal defense by producing urease and inflammatory mediators.

Question 87: Seborrheic dermatitis preferentially affects which body regions?

Elbows, knees, and sacrum
Lower extremities and dorsal feet
Palms and soles
Scalp, face, and anterior chest (Correct answer)

Correct answer: Scalp, face, and anterior chest

Seborrheic dermatitis primarily affects sebaceous gland-rich areas including the scalp, nasolabial folds, eyebrows, and anterior chest.

Question 88: A 28-year-old woman returns from Southeast Asia with cyclic fevers every 72 hours, severe anemia, and splenomegaly. Peripheral blood smear shows ring forms and banana-shaped gametocytes. Which Plasmodium species is most likely?

P. ovale
P. falciparum (Correct answer)
P. malariae
P. vivax

Correct answer: P. falciparum

P. falciparum causes 48-hour (tertian) fevers and is the only species producing banana-shaped (crescent) gametocytes; it causes the most severe malaria with high parasitemia.

Question 89: A 48-year-old man with acromegaly has elevated IGF-1 and a GH level that does not suppress to <1 ng/mL after oral glucose load. What is the first-line treatment?

Pegvisomant (GH receptor antagonist)
Octreotide (somatostatin analogue)
Dopamine agonist (cabergoline)
Transsphenoidal surgical resection (Correct answer)

Correct answer: Transsphenoidal surgical resection

Transsphenoidal surgery is the first-line treatment for acromegaly, offering the best chance of cure especially for microadenomas and non-invasive macroadenomas.

Question 90: A 55-year-old farmer develops a painless black eschar on his forearm after handling imported animal hides. Gram stain of exudate shows large gram-positive rods in chains. Which toxin mediates systemic lethality?

Exfoliative toxin
Protective antigen + lethal factor (lethal toxin) (Correct answer)
Alpha toxin (lecithinase)
Pyrogenic exotoxin A

Correct answer: Protective antigen + lethal factor (lethal toxin)

Bacillus anthracis cutaneous anthrax is caused by its AB-type toxin; protective antigen (PA) binds host cells and delivers lethal factor (a metalloprotease) or edema factor, with lethal toxin being the primary cause of death.

Question 91: A 62-year-old man with type 2 diabetes has an eGFR of 35 mL/min/1.73m². Which glucose-lowering agent should be AVOIDED due to risk of lactic acidosis?

Empagliflozin
Metformin (Correct answer)
Insulin glargine
Sitagliptin

Correct answer: Metformin

Metformin is contraindicated when eGFR falls below 30 and requires dose reduction below 45 due to accumulation and risk of lactic acidosis.

Question 92: A patient with type 2 diabetes on metformin has an HbA1c of 8.5%. The provider adds an SGLT2 inhibitor. Which additional benefit beyond glucose control supports this choice in a patient with established cardiovascular disease?

Decreased risk of major adverse cardiovascular events (Correct answer)
Reduction in HbA1c by 3%
Reversal of diabetic nephropathy
Complete elimination of hypoglycemia risk

Correct answer: Decreased risk of major adverse cardiovascular events

SGLT2 inhibitors (e.g., empagliflozin, canagliflozin) have demonstrated significant reduction in MACE and heart failure hospitalization in patients with established CVD.

Question 93: A 70-year-old man has IgM paraprotein of 4 g/dL, lymphadenopathy, bone marrow infiltration by lymphoplasmacytic cells, and hyperviscosity symptoms. What is the diagnosis?

Marginal zone lymphoma
MGUS
Waldenström macroglobulinemia (Correct answer)
Multiple myeloma

Correct answer: Waldenström macroglobulinemia

Waldenström macroglobulinemia is defined by IgM monoclonal protein plus bone marrow infiltration by lymphoplasmacytic lymphoma, commonly causing hyperviscosity.

Question 94: A 30-year-old female is diagnosed with her first episode of genital herpes. Which antiviral medication's mechanism of action relies on initial phosphorylation by a viral-encoded thymidine kinase, making it highly specific for infected cells?

Maraviroc
Foscarnet
Acyclovir (Correct answer)
Oseltamivir

Correct answer: Acyclovir

Acyclovir is a guanosine analog that is selectively effective against herpes simplex virus (HSV) and varicella-zoster virus (VZV). Its selectivity comes from the first step of its activation, which requires phosphorylation by a viral-specific thymidine kinase. [3, 6, 19] Once converted to acyclovir monophosphate, host cell kinases further phosphorylate it to the active triphosphate form, which then inhibits viral DNA polymerase and causes chain termination. [3, 6] Uninfected cells lack this viral enzyme, so the drug remains largely inactive, minimizing toxicity. [19]

Question 95: A 55-year-old woman with breast cancer develops bone pain and a corrected serum calcium of 13.8 mg/dL. The most likely mediator of humoral hypercalcemia of malignancy is:

IL-1β
1,25-dihydroxyvitamin D
PTHrP (Correct answer)
PTH

Correct answer: PTHrP

PTH-related protein (PTHrP) is secreted by many solid tumors and activates PTH receptors in bone and kidney, causing hypercalcemia without elevated true PTH.

Question 96: A 40-year-old woman develops microangiopathic hemolytic anemia, thrombocytopenia, fever, renal failure, and neurological symptoms. ADAMTS13 activity is <5%. What is the diagnosis?

DIC
Thrombotic thrombocytopenic purpura (Correct answer)
Evans syndrome
Hemolytic uremic syndrome

Correct answer: Thrombotic thrombocytopenic purpura

TTP is caused by ADAMTS13 deficiency (activity <10%), leading to ultra-large vWF multimers and platelet microthrombi causing the pentad of features.

Question 97: A 40-year-old woman has a TSH of 0.05 mIU/L and elevated free T4. She reports palpitations, heat intolerance, and a diffuse goiter with bruit on exam. What autoantibody confirms the diagnosis?

Anti-microsomal antibody
Anti-thyroglobulin
TSH receptor antibody (TRAb) (Correct answer)
Anti-thyroid peroxidase (anti-TPO)

Correct answer: TSH receptor antibody (TRAb)

TSH receptor-stimulating antibodies (TRAb) are pathognomonic for Graves' disease, causing diffuse goiter and hyperthyroidism.

Question 98: A 72-year-old female with chronic systolic heart failure has persistently elevated activity of the Renin-Angiotensin-Aldosterone System (RAAS). Which of the following is a direct pathophysiological consequence of increased Angiotensin II levels in this patient?

Inhibition of cardiac myocyte hypertrophy
Potent vasoconstriction and stimulation of aldosterone release (Correct answer)
Decreased systemic vascular resistance
Increased natriuresis and diuresis

Correct answer: Potent vasoconstriction and stimulation of aldosterone release

Angiotensin II is a powerful vasoconstrictor that increases systemic vascular resistance (afterload). It also directly stimulates the adrenal cortex to release aldosterone, which promotes sodium and water retention, further increasing blood volume and cardiac workload. These actions are maladaptive in chronic heart failure, contributing to progressive cardiac remodeling and worsening of the condition.

Question 99: Which diuretic acts on the thick ascending limb of the loop of Henle and is most effective in patients with reduced GFR?

Amiloride
Furosemide (Correct answer)
Spironolactone
Hydrochlorothiazide

Correct answer: Furosemide

Furosemide (a loop diuretic) inhibits the Na-K-2Cl cotransporter in the thick ascending limb and remains effective even with low GFR, unlike thiazides.

Question 100: A transplant patient on tacrolimus develops fever and a lung nodule with surrounding halo on CT. Bronchoalveolar lavage shows septate hyphae with acute angle branching (45°). Which antifungal is first-line?

Voriconazole (Correct answer)
Caspofungin
Fluconazole
Amphotericin B deoxycholate

Correct answer: Voriconazole

Invasive pulmonary aspergillosis in immunocompromised patients is caused by Aspergillus species (septate hyphae, 45° branching) and treated first-line with voriconazole.

Question 101: Ovarian torsion is most commonly associated with:

An ovarian cyst or mass (typically >5 cm) (Correct answer)
Endometriosis
Polycystic ovarian syndrome
Pelvic inflammatory disease

Correct answer: An ovarian cyst or mass (typically >5 cm)

Ovarian torsion most commonly occurs when an ovarian cyst or mass greater than 5 cm twists the infundibulopelvic ligament, compromising ovarian blood supply.

Question 102: A 70-year-old man develops sudden severe pain in his great toe after a night of heavy alcohol consumption. Synovial fluid analysis shows negatively birefringent needle-shaped crystals. What is the first-line acute treatment?

Methotrexate
Allopurinol
Probenecid
Indomethacin or colchicine (Correct answer)

Correct answer: Indomethacin or colchicine

Acute gout is treated with NSAIDs (e.g., indomethacin) or colchicine; urate-lowering therapy like allopurinol is not started during an acute attack.

Question 103: A patient with cervical myelopathy presents with bilateral upper extremity weakness, hand clumsiness, and hyperreflexia in the legs. What is the most appropriate initial imaging?

MRI cervical spine without contrast (Correct answer)
Plain cervical X-ray
CT myelography
EMG/nerve conduction study

Correct answer: MRI cervical spine without contrast

MRI of the cervical spine is the first-line imaging for suspected myelopathy, best demonstrating cord compression and signal changes.

Question 104: An obese 32-year-old woman arrives with ongoing right knee pain. She rejects any claims of injury, bruising, fever, rash, or general ill health. She has never experienced anything like this. She doesn't have any noteworthy medical history. She owns a woman's clothes store, which keeps her busy yet stressful. The knees are symmetrical and show no erythema, effusion, edema, or warmth. When felt, the distal femur is painful. On the right, there is less room for mobility. Over the diseased femur on an x-ray, there is a lucent, lytic lesion. Which diagnosis is more likely?

Chondrosarcoma
Osteoarthritis
Osteogenic sarcoma
Giant cell tumor of the bone (Correct answer)

Correct answer: Giant cell tumor of the bone

The patient's presentation of ongoing right knee pain, pain on palpation of the distal femur, reduced mobility, and a lucent, lytic lesion on X-ray in a young to middle-aged adult is characteristic of a giant cell tumor of the bone (GCT). GCTs are typically benign but locally aggressive tumors that commonly affect the epiphysis/metaphysis of long bones, particularly around the knee. Other options are less likely given the specific age and X-ray findings.

Question 105: A 65-year-old woman presents with bilateral hip pain that worsens with activity and is relieved by rest. X-ray shows joint space narrowing, subchondral sclerosis, and osteophytes. What is the underlying pathology?

Synovial proliferation with pannus formation
Progressive loss of articular cartilage with subchondral bone remodeling (Correct answer)
Immune complex deposition in the synovium
Urate crystal deposition in periarticular tissues

Correct answer: Progressive loss of articular cartilage with subchondral bone remodeling

Osteoarthritis is characterized by progressive articular cartilage degradation leading to subchondral sclerosis, cyst formation, and osteophyte development.

Question 106: A 60-year-old man presents with difficulty swallowing, regurgitation of food eaten hours earlier, and a gurgling mass in the neck. Barium swallow shows a posterior pharyngeal outpouching. What is the diagnosis?

Esophageal web
Achalasia
Diffuse esophageal spasm
Zenker's diverticulum (Correct answer)

Correct answer: Zenker's diverticulum

Zenker's diverticulum is a false diverticulum (pulsion type) at Killian's triangle in the posterior hypopharynx, causing regurgitation of undigested food and a palpable neck mass.

Question 107: A 45-year-old obese woman presents with recurrent right upper quadrant pain after meals. Ultrasound shows a thickened gallbladder wall with a stone impacted in the neck. She develops fever and rigors. What is the diagnosis?

Biliary colic
Ascending cholangitis
Acute cholecystitis (Correct answer)
Choledocholithiasis

Correct answer: Acute cholecystitis

Acute cholecystitis results from cystic duct obstruction by a gallstone, causing gallbladder wall inflammation, distension, and secondary bacterial infection presenting with fever and Murphy's sign.

Question 108: A 58-year-old male presents to the emergency department with severe, crushing substernal chest pain. An ECG is performed. Which of the following ECG findings is most indicative of an acute ST-segment elevation myocardial infarction (STEMI) resulting from a transmural ischemic injury?

ST-segment depression in leads V5-V6
Pathological Q waves in leads V1-V4
New ST-segment elevation at the J-point in two or more contiguous leads (Correct answer)
T-wave inversion in the inferior leads (II, III, aVF)

Correct answer: New ST-segment elevation at the J-point in two or more contiguous leads

The hallmark of an acute STEMI is ST-segment elevation on an ECG, which signifies a full-thickness (transmural) injury to the myocardium due to complete coronary artery occlusion. The criteria generally require new ST elevation at the J point in at least two contiguous leads. While other changes like Q waves or T-wave inversions can be present, the acute elevation is the defining feature for this diagnosis.

Question 109: A patient has hyponatremia with urine osmolality 550 mOsm/kg and urine sodium 60 mEq/L in the setting of recent lung cancer diagnosis. Which syndrome is most likely?

Adrenal insufficiency
Psychogenic polydipsia
Cerebral salt wasting
SIADH (Correct answer)

Correct answer: SIADH

SIADH associated with ectopic ADH production (e.g., small cell lung cancer) causes euvolemic hyponatremia with concentrated urine and high urine sodium.

Question 110: A 7-year-old unvaccinated child develops a barking cough, stridor, and low-grade fever. Lateral neck X-ray shows a 'steeple sign.' What is the causative organism?

Haemophilus influenzae type b
Parainfluenza virus (Correct answer)
Streptococcus pyogenes
Bordetella pertussis

Correct answer: Parainfluenza virus

Croup (laryngotracheobronchitis) is most commonly caused by parainfluenza virus and produces subglottic narrowing, visible as the steeple sign on AP neck X-ray.

Question 111: A pathologist examining a lymph node biopsy from a 24-year-old male with painless cervical lymphadenopathy identifies large, binucleated cells with prominent eosinophilic nucleoli, described as having an 'owl's eye' appearance. These cells are scattered within a background of reactive lymphocytes, eosinophils, and plasma cells. This pathognomonic finding is diagnostic of which malignancy?

Burkitt lymphoma
Chronic lymphocytic leukemia (CLL)
Classical Hodgkin lymphoma (Correct answer)
Follicular lymphoma

Correct answer: Classical Hodgkin lymphoma

The described cell is a classic Reed-Sternberg cell, which is the pathognomonic hallmark of classical Hodgkin lymphoma. The 'owl's eye' appearance is due to its large size, binucleation, and prominent, inclusion-like nucleoli. The presence of these cells within a mixed inflammatory background is essential for the diagnosis.

Question 112: A 45-year-old with history of alcohol abuse presents with confusion, ophthalmoplegia, and ataxia. What should be administered immediately?

Glucose bolus
Thiamine IV before glucose (Correct answer)
Naloxone IV
Lorazepam IV

Correct answer: Thiamine IV before glucose

Thiamine must be given before glucose to prevent precipitating Wernicke encephalopathy in thiamine-deficient patients.

Question 113: A 28-year-old presents with subacute confusion, psychiatric symptoms, orofacial dyskinesias, and CSF showing mild pleocytosis. What is the most likely diagnosis?

Tuberculous meningitis
Syphilitic meningitis
Herpes simplex encephalitis
Anti-NMDA receptor encephalitis (Correct answer)

Correct answer: Anti-NMDA receptor encephalitis

Anti-NMDA receptor encephalitis classically presents in young women with psychiatric prodrome, dyskinesias, autonomic instability, and CSF pleocytosis.

Question 114: A patient with hypertension is prescribed an ACE inhibitor. Which of the following describes the primary mechanism by which this class of drugs exerts its antihypertensive effect?

Promoting the release of aldosterone from the adrenal cortex
Increasing the conversion of angiotensin I to angiotensin II
Preventing the breakdown of bradykinin and reducing angiotensin II formation (Correct answer)
Blocking beta-adrenergic receptors in the myocardium

Correct answer: Preventing the breakdown of bradykinin and reducing angiotensin II formation

Angiotensin-Converting Enzyme (ACE) inhibitors work by blocking the enzyme that converts angiotensin I to angiotensin II. This reduces levels of angiotensin II, a potent vasoconstrictor, leading to vasodilation and lower blood pressure. Additionally, ACE is responsible for breaking down bradykinin, a vasodilator. By inhibiting ACE, these drugs increase bradykinin levels, which further contributes to vasodilation and the overall antihypertensive effect.

Question 115: A patient with COPD exacerbation on supplemental oxygen develops increasing somnolence. ABG shows pH 7.30, PaCO2 65 mmHg, PaO2 75 mmHg. What is the most likely cause of somnolence?

Hypercapnic narcosis from CO2 retention (Correct answer)
Medication side effect
Cerebral edema from hypoxia
Hypoxic respiratory drive abolished by oxygen

Correct answer: Hypercapnic narcosis from CO2 retention

In COPD patients with chronic hypercapnia, elevated oxygen delivery removes the hypoxic drive, leading to hypoventilation and CO2 narcosis.

Question 116: With complaints of restlessness, agitation, palpitations, sweating, and considerable weight loss of 8 pounds (without any food or exercise intervention), a 34-year-old woman who is a mother of three visits her general care physician. She also complains of fine trembling and heat sensitivity. She vehemently denies using any form of tobacco, alcohol, or caffeine. Her vital signs are as follows: 37 C (98.6 F), 120 beats per minute for her heartbeat, 140/80 mmHg for her blood pressure, and 20 beats per minute for her breathing. During a physical examination, the doctor noted a pre-tibial myxedema, lid lag, and distinctive gaze in addition to a fine tremor. The thyroid gland is lobular and diffusely enlarged upon palpation. On auscultation, a bruit is audible over the surface of the gland. TSH levels are extremely low, and radioactive iodine uptake is boosted, according to lab tests. Graves disease is identified, and potential therapies are addressed. What long-term risks are there if the patient chooses radioactive iodine therapy?

Hypothyroidism (Correct answer)
Recurrent laryngeal nerve damage
Cholestasis
Carcinoma of thyroid gland

Correct answer: Hypothyroidism

Radioactive iodine therapy (RAI) for Graves' disease works by destroying overactive thyroid cells, reducing the production of thyroid hormones. A common long-term consequence is that too much thyroid tissue is destroyed, leading to insufficient hormone production. This results in iatrogenic hypothyroidism, which then requires lifelong thyroid hormone replacement therapy.

Question 117: A 22-year-old develops fever, severe headache, petechial rash, and nuchal rigidity. CSF shows >1000 WBCs (predominantly neutrophils), low glucose, and gram-negative diplococci. Which antibiotic regimen is most appropriate?

Meropenem alone
Vancomycin + metronidazole
Ampicillin + gentamicin
Ceftriaxone + dexamethasone (Correct answer)

Correct answer: Ceftriaxone + dexamethasone

Neisseria meningitidis meningitis is treated with ceftriaxone; adjunctive dexamethasone reduces inflammation and is recommended before or with the first antibiotic dose to prevent complications.

Question 118: Podocyte injury leading to foot process effacement is the hallmark of which glomerular disease?

Membranous nephropathy
IgA nephropathy
Focal segmental glomerulosclerosis
Minimal change disease (Correct answer)

Correct answer: Minimal change disease

Minimal change disease shows diffuse podocyte foot process effacement on electron microscopy with no changes on light microscopy.

Question 119: Which spinal canal segment will exhibit secondary curves with a concavity that is reversed?

Coccyx
Cervical (Correct answer)
Sacral
Thoracic

Correct answer: Cervical

The vertebral column has four natural curves: two primary (thoracic and sacral) and two secondary (cervical and lumbar). Primary curves are concave anteriorly (kyphotic), while secondary curves are concave posteriorly (lordotic). Therefore, the cervical segment, being a secondary curve, exhibits a lordotic curve, meaning its concavity is reversed compared to the primary curves, presenting anteriorly.

Question 120: A 60-year-old man has lymphadenopathy, hepatosplenomegaly, WBC 80,000/μL with 95% mature small lymphocytes, and positive CD5/CD23 by flow cytometry. What is the diagnosis?

Hairy cell leukemia
Mantle cell lymphoma
Chronic lymphocytic leukemia (Correct answer)
Follicular lymphoma

Correct answer: Chronic lymphocytic leukemia

CLL is characterized by clonal proliferation of mature CD5+/CD23+ B lymphocytes with absolute lymphocytosis; mantle cell lymphoma is CD5+ but CD23−.

Question 121: A patient develops fever, productive cough, and consolidation 5 days after intubation for trauma. BAL culture grows Pseudomonas aeruginosa. Which antibiotic regimen is most appropriate?

Meropenem monotherapy
Levofloxacin monotherapy
Cefepime plus tobramycin (Correct answer)
Vancomycin plus piperacillin-tazobactam

Correct answer: Cefepime plus tobramycin

Ventilator-associated pneumonia caused by Pseudomonas requires double-coverage with an antipseudomonal beta-lactam plus an aminoglycoside or fluoroquinolone to reduce resistance risk.

Question 122: Tinea versicolor (pityriasis versicolor) is caused by which organism?

Malassezia furfur (Correct answer)
Candida albicans
Trichophyton rubrum
Epidermophyton floccosum

Correct answer: Malassezia furfur

Tinea versicolor is caused by Malassezia furfur, a lipophilic dimorphic yeast that normally colonizes the skin's stratum corneum.

Question 123: Which metabolic acidosis pattern is expected in a patient with uncontrolled type 1 diabetes presenting in DKA?

High anion gap metabolic acidosis (Correct answer)
Respiratory alkalosis
Metabolic alkalosis with respiratory acidosis
Normal anion gap metabolic acidosis

Correct answer: High anion gap metabolic acidosis

DKA produces ketoacids (beta-hydroxybutyrate, acetoacetate) that consume bicarbonate and elevate the anion gap.

Question 124: Which investigation is most specific for diagnosing herpes simplex encephalitis?

MRI FLAIR signal in temporal lobes
Serum HSV antibody titer
EEG showing periodic lateralized epileptiform discharges
CSF HSV PCR (Correct answer)

Correct answer: CSF HSV PCR

CSF HSV PCR has high sensitivity and specificity (>95%) and is the gold standard for diagnosing herpes simplex encephalitis.

Question 125: Acne vulgaris is primarily caused by which organism?

Streptococcus pyogenes
Cutibacterium acnes (Correct answer)
Staphylococcus aureus
Malassezia furfur

Correct answer: Cutibacterium acnes

Acne vulgaris is primarily caused by Cutibacterium acnes (formerly Propionibacterium acnes), which colonizes hair follicles in sebum-rich areas.

Question 126: A 50-year-old presents with hemoptysis and a chest X-ray showing left lower lobe atelectasis with a central mass. Bronchoscopy reveals a carcinoid tumor. Which histologic finding would classify this as typical rather than atypical carcinoid?

Fewer than 2 mitoses per 10 HPF with no necrosis (Correct answer)
Greater than 10 mitoses per 10 HPF
Ki-67 index greater than 20%
Necrosis present with 3-10 mitoses per 10 HPF

Correct answer: Fewer than 2 mitoses per 10 HPF with no necrosis

Typical carcinoid is defined by fewer than 2 mitoses per 10 HPF and absence of necrosis; atypical carcinoid has 2-10 mitoses per 10 HPF or necrosis.

Question 127: A 72-year-old with COPD and recurrent exacerbations (3 in past year) has FEV1 of 35% predicted and blood eosinophils of 320 cells/μL on dual LABA/LAMA therapy. Which is the most appropriate step-up?

Add inhaled corticosteroid (triple therapy) (Correct answer)
Initiate long-term oral corticosteroids
Add roflumilast
Start azithromycin prophylaxis

Correct answer: Add inhaled corticosteroid (triple therapy)

In COPD patients with frequent exacerbations and eosinophil count ≥300 cells/μL on dual bronchodilation, adding ICS (triple therapy) reduces exacerbation frequency.

Question 128: Which feature best distinguishes a Todd's paralysis from an acute ischemic stroke?

Gradual resolution over minutes to hours after a seizure (Correct answer)
Age of the patient
Elevated blood pressure
Presence of headache

Correct answer: Gradual resolution over minutes to hours after a seizure

Todd's paralysis is postictal focal weakness that resolves spontaneously within minutes to hours following a seizure.

Question 129: A 7-year-old boy has persistent inability to focus, hyperactivity, and impulsiveness affecting school performance since age 5. ADHD is confirmed. What is the first-line pharmacological treatment?

Methylphenidate (Correct answer)
Fluoxetine
Risperidone
Clonidine

Correct answer: Methylphenidate

Stimulant medications such as methylphenidate are the first-line pharmacological treatment for ADHD in school-aged children, typically combined with behavioral therapy for optimal outcomes.

Question 130: A 48-year-old woman presents with widespread musculoskeletal pain for 6 months, fatigue, and sleep disturbance. Physical examination reveals 14/18 tender points. Lab work is normal. What is the mechanism of her condition?

Central sensitization with amplified pain processing (Correct answer)
Muscle fiber necrosis
Crystal deposition in tendons
Autoimmune synovitis

Correct answer: Central sensitization with amplified pain processing

Fibromyalgia is characterized by central sensitization — amplified central pain processing — rather than peripheral inflammation, explaining normal lab results and diffuse tenderness.

Question 131: A patient with schizophrenia on haloperidol develops involuntary repetitive movements of the face, tongue, and extremities after 3 years of treatment. What is this condition?

Akathisia
Parkinsonism
Acute dystonia
Tardive dyskinesia (Correct answer)

Correct answer: Tardive dyskinesia

Tardive dyskinesia is a late-onset movement disorder from prolonged dopamine receptor blockade, typically presenting with oro-facial dyskinesias.

Question 132: A 45-year-old female presents to the emergency department with a severe asthma exacerbation, refractory to initial treatment with nebulized albuterol/ipratropium and systemic corticosteroids. She is tachypneic and speaking in single words. Which of the following intravenous medications is most appropriate to administer as an adjunctive therapy in this situation?

Magnesium sulfate (Correct answer)
Aminophylline
Sodium bicarbonate
Furosemide

Correct answer: Magnesium sulfate

For severe asthma exacerbations not responding to initial standard therapies (SABAs, anticholinergics, and systemic corticosteroids), intravenous magnesium sulfate is recommended as an adjunctive treatment. It has bronchodilatory properties and can improve lung function and reduce hospitalization rates in severe cases. Furosemide is a diuretic, aminophylline is rarely used due to its narrow therapeutic index and significant side effects, and sodium bicarbonate is not indicated for asthma.

Question 133: A 60-year-old woman on long-term corticosteroids develops back pain. DEXA scan shows T-score of -2.8. Which medication addresses the underlying pathophysiology of her bone loss?

Calcium supplementation alone
Vitamin D supplementation alone
Calcitonin
Alendronate (bisphosphonate) (Correct answer)

Correct answer: Alendronate (bisphosphonate)

Bisphosphonates inhibit osteoclast-mediated bone resorption and are first-line for glucocorticoid-induced osteoporosis with T-score ≤-2.5.

Question 134: Which test is most sensitive for detecting early iron deficiency before anemia develops?

Hemoglobin
Serum ferritin (Correct answer)
Serum iron
MCV

Correct answer: Serum ferritin

Serum ferritin falls first in iron deficiency, reflecting depleted iron stores before iron-restricted erythropoiesis and anemia develop.

Question 135: A 60-year-old woman with osteoporosis has a serum calcium of 11.8 mg/dL, low phosphorus, and PTH of 120 pg/mL. Neck ultrasound shows a right inferior parathyroid adenoma. What is the definitive treatment?

Cinacalcet indefinitely
Bisphosphonate therapy
Thiazide diuretics to increase calcium reabsorption
Parathyroidectomy (Correct answer)

Correct answer: Parathyroidectomy

Parathyroidectomy is the definitive curative treatment for symptomatic primary hyperparathyroidism, including cases with osteoporosis or nephrolithiasis.

Question 136: The ABCDE criteria for melanoma screening stands for:

Asymmetry, Blistering, Cells, Dermis, Elevation
Area, Border, Circumference, Depth, Erythema
Age, Bleeding, Color, Diameter, Evolution
Asymmetry, Border, Color, Diameter, Evolution (Correct answer)

Correct answer: Asymmetry, Border, Color, Diameter, Evolution

ABCDE stands for Asymmetry, Border irregularity, Color variation, Diameter greater than 6 mm, and Evolution of the lesion.

Question 137: Which classic description applies to varicella (chickenpox) skin lesions?

Honey-colored crusted vesicles
Dew drops on a rose petal (Correct answer)
Target lesions with central clearing
Silvery-scaled papules on elbows

Correct answer: Dew drops on a rose petal

Varicella lesions are classically described as 'dew drops on a rose petal' — clear vesicles on an erythematous base at various stages of evolution.

Question 138: A 45-year-old man has hypertension, hypokalemia, and a plasma aldosterone-to-renin ratio of 35 (elevated). What is the most likely diagnosis?

Primary hyperaldosteronism (Conn's syndrome) (Correct answer)
Cushing's syndrome
Pheochromocytoma
Renovascular hypertension

Correct answer: Primary hyperaldosteronism (Conn's syndrome)

An elevated aldosterone-to-renin ratio with hypokalemia and hypertension is the hallmark of primary hyperaldosteronism due to autonomous aldosterone secretion.

Question 139: A 50-year-old with a history of hypertension develops sudden onset of rotatory vertigo, nausea, and inability to walk. There is nystagmus and ipsilateral limb ataxia. Which structure is most likely affected?

Vestibular nerve
Brainstem (pons)
Cerebellum (posterior inferior) (Correct answer)
Cochlea

Correct answer: Cerebellum (posterior inferior)

Sudden vertigo with ipsilateral limb ataxia and inability to walk points to cerebellar infarction in the PICA territory, which is a stroke emergency.

Question 140: Placenta previa (placenta overlying the internal os) is best diagnosed by:

Digital cervical examination
Pelvic MRI
Transvaginal ultrasound (Correct answer)
Transabdominal ultrasound

Correct answer: Transvaginal ultrasound

Transvaginal ultrasound is the gold standard for diagnosing placenta previa, providing accurate measurement of the placental edge-to-internal os distance.

Question 141: A 60-year-old construction worker in the Southwest US develops fever, chest pain, eosinophilia, and a coin lesion on CXR after exposure to soil dust. Serology is positive. Which organism is responsible?

Histoplasma capsulatum
Coccidioides immitis (Correct answer)
Aspergillus fumigatus
Blastomyces dermatitidis

Correct answer: Coccidioides immitis

Coccidioides immitis is endemic to the arid Southwest US (San Joaquin Valley fever) and causes pulmonary infection with eosinophilia; large endosporulating spherules are the tissue form.

Question 142: A 72-year-old woman presents with acute knee pain and swelling. Synovial fluid shows positively birefringent rhomboid-shaped crystals under polarized light. What is the diagnosis?

Hemarthrosis
Gout
Pseudogout (calcium pyrophosphate deposition disease) (Correct answer)
Septic arthritis

Correct answer: Pseudogout (calcium pyrophosphate deposition disease)

Calcium pyrophosphate dihydrate (CPPD) crystals are positively birefringent and rhomboid-shaped, distinguishing pseudogout from gout's negatively birefringent needle-shaped urate crystals.

Question 143: A patient presents with cola-colored urine, periorbital edema, hypertension, and hematuria 2 weeks after a strep throat infection. What is the most likely diagnosis?

Membranoproliferative GN
IgA nephropathy
Henoch-Schönlein purpura nephritis
Post-streptococcal glomerulonephritis (Correct answer)

Correct answer: Post-streptococcal glomerulonephritis

Post-streptococcal GN occurs 1-3 weeks after pharyngitis, presenting with nephritic syndrome and is the classic post-infectious GN in children.

Question 144: A 55-year-old with scleroderma develops progressive exertional dyspnea. Echocardiogram shows RVSP of 55 mmHg. Right heart catheterization confirms mPAP of 38 mmHg with normal PCWP. What is the most appropriate initial therapy?

Subcutaneous treprostinil
Intravenous epoprostenol
Oral sildenafil (Correct answer)
Oral bosentan

Correct answer: Oral sildenafil

For WHO functional class II-III pulmonary arterial hypertension, oral PDE-5 inhibitors like sildenafil or ERA like ambrisentan/bosentan are recommended initial therapy.

Question 145: What is the most common type of skin cancer in the United States?

Squamous cell carcinoma
Basal cell carcinoma (Correct answer)
Melanoma
Merkel cell carcinoma

Correct answer: Basal cell carcinoma

Basal cell carcinoma is the most common skin cancer in the US, accounting for approximately 80% of all skin cancers.

Question 146: A 45-year-old man has recurrent calcium oxalate kidney stones. Urinalysis shows hypercalciuria with normal serum calcium. Which dietary modification is most appropriate?

Decrease fluid intake
Increase oxalate-rich foods
Restrict dietary calcium severely
Increase dietary calcium intake (Correct answer)

Correct answer: Increase dietary calcium intake

Adequate dietary calcium binds oxalate in the gut, reducing intestinal oxalate absorption and urinary oxalate excretion.

Question 147: A 45-year-old asymptomatic woman with no family history of colorectal cancer (CRC) presents for a routine physical. According to the current guidelines from the U.S. Preventive Services Task Force (USPSTF), what is the recommended age to begin average-risk CRC screening?

55 years
45 years (Correct answer)
40 years
50 years

Correct answer: 45 years

In May 2021, the U.S. Preventive Services Task Force (USPSTF) updated its guidelines, lowering the recommended age to begin colorectal cancer screening for average-risk individuals from 50 to 45 years. This change was based on data showing an increasing incidence of CRC in younger adults.

Question 148: A patient with renal cell carcinoma has polycythemia. What is the mechanism?

Dehydration causing hemoconcentration
Iron deficiency causing compensatory erythropoiesis
Paraneoplastic PTHrP secretion
Tumor secretion of EPO leading to increased RBC production (Correct answer)

Correct answer: Tumor secretion of EPO leading to increased RBC production

RCC can autonomously secrete erythropoietin as a paraneoplastic syndrome, stimulating erythropoiesis and causing polycythemia.

Question 149: A 35-year-old woman with SLE develops proximal muscle weakness and a heliotrope rash around her eyes. Creatine kinase is markedly elevated. Which autoantibody is most specific for her inflammatory myopathy?

Anti-Smith
Anti-Jo-1 (Correct answer)
Anti-Ro/SSA
Anti-dsDNA

Correct answer: Anti-Jo-1

Anti-Jo-1 (anti-synthetase antibody) is the most specific marker for polymyositis/dermatomyositis and is associated with interstitial lung disease.

Question 150: A 45-year-old female is diagnosed with Autosomal Dominant Polycystic Kidney Disease (ADPKD) after an incidental finding of multiple bilateral renal cysts on an abdominal ultrasound. Which of the following is the most accurate description of the underlying pathophysiology of this condition?

Deposition of immune complexes in the glomeruli, causing inflammatory damage and cyst formation.
Mutations in genes encoding for collagen type IV, leading to a weakened glomerular basement membrane.
Chronic obstruction of the urinary tract leading to back pressure and cystic dilation of the nephrons.
Mutations in PKD1 or PKD2 genes, leading to abnormal ciliary function, altered tubular cell proliferation, and fluid secretion into cysts. (Correct answer)

Correct answer: Mutations in PKD1 or PKD2 genes, leading to abnormal ciliary function, altered tubular cell proliferation, and fluid secretion into cysts.

ADPKD is primarily caused by mutations in the PKD1 (encoding polycystin-1) or PKD2 (encoding polycystin-2) genes. These proteins are crucial for the normal function of renal tubular cilia, which act as mechanosensors. Dysfunction of these cilia leads to abnormal intracellular signaling (e.g., increased cAMP), resulting in increased cell proliferation, fluid secretion, and the progressive formation and enlargement of renal cysts.

Question 151: A 35-year-old woman presents with episodic unilateral headache, nausea, photophobia, and phonophobia lasting 4-72 hours. She notes visual aura preceding attacks. What is the classification?

Tension-type headache
Cluster headache
Trigeminal neuralgia
Migraine with aura (Correct answer)

Correct answer: Migraine with aura

Recurrent unilateral headache with nausea, photophobia, and preceding visual aura fulfills criteria for migraine with aura.

Question 152: A 72-year-old woman is diagnosed with osteoporosis after a DEXA scan reveals a T-score of -2.8 at the femoral neck. She has no contraindications to standard therapy. Which of the following best describes the mechanism of action of bisphosphonates, the first-line treatment for this condition?

Stimulates osteoblasts to increase bone formation
Increases intestinal calcium absorption and renal calcium reabsorption
Acts as a selective estrogen receptor modulator in bone
Inhibits osteoclast-mediated bone resorption (Correct answer)

Correct answer: Inhibits osteoclast-mediated bone resorption

Bisphosphonates are potent inhibitors of bone resorption. They bind to hydroxyapatite in bone and are taken up by osteoclasts, where they interfere with cellular processes, leading to osteoclast apoptosis. This action reduces the breakdown of bone, allowing for a net increase in bone density. Teriparatide stimulates osteoblasts, raloxifene is a SERM, and parathyroid hormone (in a complex way) and Vitamin D metabolites increase calcium absorption.

Question 153: The suffix '-plasty' means:

Surgical repair or reconstruction (Correct answer)
Surgical examination
Surgical removal
Surgical incision

Correct answer: Surgical repair or reconstruction

-Plasty refers to surgical repair or reconstruction of a body part.

Question 154: Which drug class is contraindicated in a patient with bilateral renal artery stenosis who has hypertension?

ACE inhibitors (Correct answer)
Calcium channel blockers
Beta-blockers
Thiazide diuretics

Correct answer: ACE inhibitors

ACE inhibitors block angiotensin II–mediated efferent arteriolar constriction, which is essential to maintain GFR in bilateral renal artery stenosis, causing acute kidney injury.

Question 155: A 68-year-old man with painless jaundice, clay-colored stools, and a palpable, non-tender gallbladder is most likely to have which diagnosis?

Choledocholithiasis
Carcinoma of the head of the pancreas (Correct answer)
Acute cholecystitis
Primary sclerosing cholangitis

Correct answer: Carcinoma of the head of the pancreas

Painless jaundice with a palpable, non-tender gallbladder (Courvoisier's sign) strongly suggests malignant biliary obstruction, most commonly pancreatic head carcinoma.

Question 156: A patient presents with flank pain, hematuria, and a palpable abdominal mass. CT reveals a large renal mass with internal fat density. What is the most likely diagnosis?

Angiomyolipoma (Correct answer)
Wilms tumor
Transitional cell carcinoma
Renal cell carcinoma

Correct answer: Angiomyolipoma

Fat density on CT is characteristic of angiomyolipoma, a benign hamartoma composed of blood vessels, smooth muscle, and fat.

Question 157: A 45-year-old female presents with a 6-month history of symmetric pain and swelling in her metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints, associated with morning stiffness lasting over an hour. Which of the following laboratory findings is most specific for the diagnosis of rheumatoid arthritis?

Positive anti-cyclic citrullinated peptide (anti-CCP) antibody (Correct answer)
Elevated C-reactive protein (CRP)
Elevated rheumatoid factor (RF)
Positive antinuclear antibody (ANA)

Correct answer: Positive anti-cyclic citrullinated peptide (anti-CCP) antibody

While RF, CRP, and ANA can be positive in rheumatoid arthritis, anti-CCP antibodies have the highest specificity (around 95-98%) for the disease. RF can be positive in other autoimmune diseases, infections, and even healthy individuals. CRP is a nonspecific marker of inflammation. ANA is more characteristic of SLE but can be seen in RA.

Question 158: A pathologist is examining brain tissue from a patient who had severe dementia. The microscopic examination reveals numerous extracellular neuritic plaques and intracellular neurofibrillary tangles, particularly in the hippocampus and neocortex. These findings are the classic neuropathological hallmarks of which condition?

Creutzfeldt-Jakob Disease
Alzheimer's Disease (Correct answer)
Lewy Body Dementia
Huntington's Disease

Correct answer: Alzheimer's Disease

The two cardinal neuropathological lesions that define Alzheimer's Disease are extracellular plaques composed of beta-amyloid peptide and intracellular neurofibrillary tangles composed of hyperphosphorylated tau protein. Lewy Body Dementia is characterized by alpha-synuclein aggregates (Lewy bodies). Creutzfeldt-Jakob disease shows spongiform changes and prion protein deposition. Huntington's disease is characterized by neuronal loss and gliosis in the caudate and putamen due to mutant huntingtin protein.

Question 159: Allergic contact dermatitis is a type IV hypersensitivity reaction mediated by:

Neutrophil infiltration
IgE antibodies and mast cells
IgG antibodies and complement
T lymphocytes (delayed-type) (Correct answer)

Correct answer: T lymphocytes (delayed-type)

Allergic contact dermatitis is a type IV (cell-mediated/delayed-type) hypersensitivity reaction mediated by sensitized T lymphocytes.

Question 160: A 35-year-old woman with SLE has red cell casts and nephritic syndrome. Biopsy shows wire loop lesions and subendothelial deposits. What class of lupus nephritis is this?

Class IV (diffuse proliferative) (Correct answer)
Class II (mesangial proliferative)
Class III (focal proliferative)
Class V (membranous)

Correct answer: Class IV (diffuse proliferative)

Class IV lupus nephritis is the most severe form, characterized by diffuse proliferative changes with wire loop lesions from subendothelial immune complex deposits.

Question 161: A 32-year-old man presents with painless cervical lymphadenopathy. Biopsy reveals Reed-Sternberg cells with owl-eye nucleoli in a background of lymphocytes. Which immunophenotype is characteristic of these cells?

CD5+, CD23+
CD20+, CD3−
CD10+, BCL2+
CD15+, CD30+, CD45− (Correct answer)

Correct answer: CD15+, CD30+, CD45−

Reed-Sternberg cells in classical Hodgkin lymphoma are CD15+/CD30+ and characteristically CD45− (leukocyte common antigen negative).

Question 162: A 55-year-old man with gout has recurrent attacks despite dietary modification. Serum uric acid is 9.8 mg/dL. Which enzyme deficiency would cause this hyperuricemia through overproduction rather than underexcretion?

Hypoxanthine-guanine phosphoribosyltransferase (HGPRT) deficiency (Correct answer)
Glucose-6-phosphatase deficiency
Adenosine deaminase deficiency
Purine nucleoside phosphorylase deficiency

Correct answer: Hypoxanthine-guanine phosphoribosyltransferase (HGPRT) deficiency

HGPRT deficiency (Lesch-Nyhan syndrome partial form) leads to decreased purine salvage and excess de novo purine synthesis, causing uric acid overproduction.

Question 163: Which topical agent is considered first-line for mild-to-moderate acne vulgaris?

Isotretinoin
Oral tetracycline
Triamcinolone
Benzoyl peroxide (Correct answer)

Correct answer: Benzoyl peroxide

Benzoyl peroxide is first-line topical treatment for mild-to-moderate acne due to its antibacterial, keratolytic, and comedolytic properties.

Question 164: A 52-year-old presents with dyspnea and oxygen saturation of 88% at rest. ABG shows pH 7.32, PaCO2 58 mmHg, PaO2 52 mmHg, HCO3 28 mEq/L. Chest X-ray shows hyperinflation. What is the most appropriate initial ventilatory support?

Simple face mask at 40% FiO2
Noninvasive positive pressure ventilation (NPPV/BiPAP) (Correct answer)
High-flow nasal cannula oxygen
Immediate intubation and invasive mechanical ventilation

Correct answer: Noninvasive positive pressure ventilation (NPPV/BiPAP)

Noninvasive positive pressure ventilation is the preferred initial ventilatory support for acute hypercapnic respiratory failure in COPD exacerbation, reducing intubation rates and mortality.

Question 165: A 28-year-old woman of Mediterranean descent presents with lifelong mild fatigue. A CBC reveals: Hgb 10.5 g/dL, MCV 65 fL, RBC 5.8 million/µL, and a normal RDW. Iron studies show a serum ferritin of 80 ng/mL and a transferrin saturation of 30%. Which of the following is the most likely diagnosis?

Sideroblastic anemia
Anemia of chronic disease
Beta-thalassemia trait (Correct answer)
Iron deficiency anemia

Correct answer: Beta-thalassemia trait

The patient presents with microcytic anemia (MCV < 80 fL). Key differentiating features point towards thalassemia trait: a markedly low MCV with a disproportionately high RBC count, a normal RDW, and normal iron studies. The Mentzer Index (MCV/RBC) is < 13 (65/5.8 ≈ 11.2), which is highly suggestive of thalassemia trait rather than iron deficiency anemia, where it is typically > 13. Her Mediterranean ancestry also increases the pre-test probability for beta-thalassemia.

Question 166: A 65-year-old man presents with a 3-day history of fever, productive cough, and shortness of breath. A chest x-ray confirms a right lower lobe infiltrate. His vitals are: RR 32/min, BP 88/55 mmHg, and he is newly confused. His BUN is 25 mg/dL. Based on the CURB-65 score, what is the most appropriate management setting for this patient with community-acquired pneumonia (CAP)?

Outpatient management with oral antibiotics.
Consideration for outpatient management with close follow-up.
Inpatient hospital admission to a general medical ward.
Inpatient hospital admission, likely to the ICU. (Correct answer)

Correct answer: Inpatient hospital admission, likely to the ICU.

The CURB-65 score helps determine the severity and mortality risk of community-acquired pneumonia. The patient scores 1 point for Confusion, 1 for Urea (>7 mmol/L or ~19.6 mg/dL), 1 for Respiratory rate (≥30/min), and 1 for Blood pressure (systolic <90 or diastolic ≤60). His age (≥65) is not given as a factor in the stem, but even with these 4 points, his score is ≥3. A score of 3 or more indicates high-risk CAP with high mortality, warranting urgent inpatient admission and consideration for ICU level of care.

Question 167: A 35-year-old woman develops progressive dyspnea and bilateral hilar lymphadenopathy on chest X-ray. Biopsy shows noncaseating granulomas. Which finding would most strongly indicate need for systemic corticosteroid treatment?

Löfgren syndrome presentation
Hypercalcemia with renal involvement (Correct answer)
Erythema nodosum with arthralgia
Asymptomatic bilateral hilar adenopathy

Correct answer: Hypercalcemia with renal involvement

Hypercalcemia with renal involvement in sarcoidosis requires systemic corticosteroids to prevent nephrocalcinosis and renal failure.

Question 168: A patient with moderate persistent asthma is well-controlled on medium-dose ICS/LABA. She is planning pregnancy. What is the most appropriate medication adjustment?

Continue current regimen (Correct answer)
Discontinue LABA and continue ICS alone
Switch to montelukast monotherapy
Reduce to low-dose ICS only

Correct answer: Continue current regimen

Well-controlled asthma during pregnancy should be maintained on current therapy, as uncontrolled asthma poses greater risk to mother and fetus than ICS/LABA.

Question 169: A 19-year-old woman with a BMI of 17 has oligomenorrhea and labs showing low FSH, LH, and estradiol with normal TSH and prolactin. What is the most likely cause of her hypogonadism?

Polycystic ovary syndrome
Hypothalamic amenorrhea (functional) (Correct answer)
Premature ovarian insufficiency
Hyperprolactinemia

Correct answer: Hypothalamic amenorrhea (functional)

Low body weight and energy deficit suppress GnRH pulse frequency, causing hypothalamic amenorrhea with low FSH, LH, and estradiol.

Question 170: Renal tubular acidosis type IV is caused by which mechanism?

Carbonic anhydrase deficiency
Hypoaldosteronism impairing K+ and H+ excretion (Correct answer)
Defective distal H+ secretion
Defective proximal HCO3 reabsorption

Correct answer: Hypoaldosteronism impairing K+ and H+ excretion

Type IV RTA results from aldosterone deficiency or resistance, impairing both K+ and H+ secretion in the collecting duct, causing hyperkalemia and a normal anion gap acidosis.

Question 171: A 34-year-old woman presents with chronic diarrhea, bloating, and significant weight loss. Serological testing is positive for IgA anti-tissue transglutaminase (tTG) antibodies. An upper endoscopy with duodenal biopsy is performed. Which of the following biopsy findings would confirm the diagnosis of celiac disease?

Villous atrophy, crypt hyperplasia, and increased intraepithelial lymphocytes (Correct answer)
Foamy macrophages within the lamina propria
Glandular atrophy and intestinal metaplasia
Transmural inflammation with skip lesions

Correct answer: Villous atrophy, crypt hyperplasia, and increased intraepithelial lymphocytes

The classic histopathological triad for celiac disease on a duodenal biopsy is villous atrophy, crypt hyperplasia, and an increase in intraepithelial lymphocytes. This combination confirms the diagnosis in the setting of positive serology. Glandular atrophy and intestinal metaplasia are seen in conditions like atrophic gastritis. Foamy macrophages are characteristic of Whipple disease. Transmural inflammation with skip lesions is a feature of Crohn's disease.

Question 172: Which acid-base disturbance is associated with contraction alkalosis caused by loop diuretics?

Mixed respiratory and metabolic acidosis
Metabolic alkalosis with hypokalemia (Correct answer)
Respiratory alkalosis with hypocapnia
Metabolic acidosis with increased anion gap

Correct answer: Metabolic alkalosis with hypokalemia

Loop diuretics cause loss of NaCl-rich fluid, volume contraction, and secondary hyperaldosteronism, leading to metabolic alkalosis and hypokalemia.

Question 173: A patient with severe COPD exacerbation is placed on supplemental oxygen. After 30 minutes, he becomes drowsy and his PaCO2 rises from 55 to 75 mmHg. What is the most likely mechanism?

Worsening bronchospasm from oxygen
Loss of hypoxic pulmonary vasoconstriction causing increased V/Q mismatch (Haldane effect) (Correct answer)
Pneumonia worsening secretions
Oxygen-induced cardiac depression

Correct answer: Loss of hypoxic pulmonary vasoconstriction causing increased V/Q mismatch (Haldane effect)

High-flow O2 in chronic CO2 retainers causes the Haldane effect (CO2 displaced from hemoglobin) and worsens V/Q mismatch by reversing hypoxic pulmonary vasoconstriction, raising PaCO2.

Question 174: A 22-year-old woman has a lifelong history of heavy menstrual bleeding, prolonged bleeding after dental procedures, and a normal PT and platelet count but prolonged aPTT and PFA-100 closure time. von Willebrand factor antigen is 35% (low). What is the most likely diagnosis?

Hemophilia A
Bernard-Soulier syndrome
Glanzmann thrombasthenia
Type 1 von Willebrand disease (Correct answer)

Correct answer: Type 1 von Willebrand disease

Type 1 VWD is the most common inherited bleeding disorder, characterized by quantitative reduction of VWF causing mucocutaneous bleeding with prolonged PFA-100 and aPTT.

Question 175: A 45-year-old man with a history of a recent dental procedure followed by a prolonged course of clindamycin presents with profuse, watery, non-bloody diarrhea and lower abdominal cramping. Stool assay is positive for toxins A and B. What is the primary mechanism of action of these toxins produced by the causative organism?

Activation of adenylate cyclase, leading to increased intracellular cAMP and massive fluid secretion.
Inhibition of protein synthesis by blocking the EF-2 translocation step.
Superantigen activity, leading to widespread T-cell activation and cytokine release.
Inactivation of Rho family GTPases, causing cytoskeletal disruption and epithelial cell death. (Correct answer)

Correct answer: Inactivation of Rho family GTPases, causing cytoskeletal disruption and epithelial cell death.

The patient's presentation is classic for Clostridioides difficile infection (CDI), often precipitated by antibiotics like clindamycin. The primary virulence factors are Toxin A (TcdA) and Toxin B (TcdB), which are glucosyltransferases. They inactivate small GTP-binding proteins of the Rho family within intestinal epithelial cells, leading to actin cytoskeleton disruption, cell rounding, apoptosis, and loss of epithelial barrier function, which results in colitis and diarrhea. [1, 7, 9]

Question 176: A patient develops ascending paralysis 2 weeks after a GI infection with Campylobacter jejuni. CSF shows albuminocytologic dissociation. Which antibody is associated with this variant?

Anti-GQ1b
Anti-MAG
Anti-GD1b
Anti-GM1 (Correct answer)

Correct answer: Anti-GM1

Anti-GM1 antibodies are associated with the acute motor axonal neuropathy (AMAN) variant of Guillain-Barré syndrome linked to Campylobacter.

Question 177: A 28-year-old traveler to Mexico develops profuse watery 'rice-water' diarrhea with no fecal leukocytes. The causative organism produces a toxin that permanently activates Gs protein by ADP-ribosylation. Which organism?

Vibrio cholerae (Correct answer)
Campylobacter jejuni
Enterotoxigenic E. coli
Salmonella typhi

Correct answer: Vibrio cholerae

Vibrio cholerae produces cholera toxin, which ADP-ribosylates the Gs alpha subunit, locking adenylyl cyclase in the 'on' position, causing massive cAMP-driven chloride and water secretion.

Question 178: A 6-year-old develops red strawberry tongue, scarlatiniform rash, and perioral pallor. Throat swab grows beta-hemolytic group A streptococcus. Which complication can be prevented by treating with penicillin?

Peritonsillar abscess
Toxic shock syndrome
Post-streptococcal glomerulonephritis
Rheumatic fever (Correct answer)

Correct answer: Rheumatic fever

Antibiotic treatment of group A streptococcal pharyngitis prevents acute rheumatic fever (but NOT post-streptococcal glomerulonephritis, which is not prevented by antibiotics).

Question 179: A 28-year-old African American female presents with fatigue, a facial rash that worsens with sun exposure, and joint pain in her hands and wrists. Laboratory workup is initiated for a suspected autoimmune condition. Which of the following clinical findings is most characteristic of Systemic Lupus Erythematosus (SLE)?

Proximal muscle weakness
Asymmetric oligoarthritis
Painless oral ulcers (Correct answer)
Sclerodactyly

Correct answer: Painless oral ulcers

Painless oral or nasopharyngeal ulcers are a specific clinical criterion for the diagnosis of SLE according to both the ACR and SLICC classification systems. While symmetric small joint arthritis is common in SLE, asymmetric oligoarthritis is more characteristic of spondyloarthropathies. Proximal muscle weakness is characteristic of myositis, and sclerodactyly (thickening and tightening of the skin on the fingers) is a hallmark feature of systemic sclerosis.

Question 180: Which of the following describes how goblet cells and enteroendocrine cells are different?

Use of exocytosis for release of secretory products from the cell
The direction of release of secretion (Correct answer)
Their origin form a crypt stem cell
Their presence in small and large intestine

Correct answer: The direction of release of secretion

Both goblet cells and enteroendocrine cells originate from crypt stem cells and use exocytosis to release their secretory products. However, their direction of secretion differs significantly. Goblet cells secrete mucus onto the apical surface into the intestinal lumen, while enteroendocrine cells secrete hormones into the basolateral side, which then enter the bloodstream to act on distant targets.

Question 181: Which complication is most feared in a patient with Barrett's esophagus?

Squamous cell carcinoma of the esophagus
Mallory-Weiss tear
Esophageal perforation
Adenocarcinoma of the esophagus (Correct answer)

Correct answer: Adenocarcinoma of the esophagus

Barrett's esophagus involves intestinal metaplasia of the lower esophageal epithelium and is a precursor to esophageal adenocarcinoma.

Question 182: A patient with cirrhosis develops acute upper GI bleeding. Endoscopy reveals tortuous, dilated submucosal veins at the gastroesophageal junction. What is the pathophysiologic mechanism?

Aortoenteric fistula formation
Portal hypertension causing portosystemic shunting (Correct answer)
Mesenteric ischemia
Increased arterial blood flow to the esophagus

Correct answer: Portal hypertension causing portosystemic shunting

Portal hypertension from cirrhosis causes blood to shunt through portosystemic collaterals including esophageal varices, which are prone to rupture.

Question 183: A 30-year-old woman has episodic hemolysis, pancytopenia, and venous thrombosis. Flow cytometry shows absence of CD55 and CD59 on RBCs. What is the defect?

GPI anchor deficiency (Correct answer)
Pyruvate kinase deficiency
Spectrin mutation
Band 3 protein loss

Correct answer: GPI anchor deficiency

Paroxysmal nocturnal hemoglobinuria (PNH) results from a PIGA mutation causing GPI anchor deficiency, rendering cells vulnerable to complement-mediated lysis.

Question 184: Which tumor lysis syndrome lab abnormality can directly cause fatal cardiac arrhythmias?

Hypocalcemia
Hyperkalemia (Correct answer)
Hyperuricemia
Hyperphosphatemia

Correct answer: Hyperkalemia

Hyperkalemia from massive cell lysis is the most immediately life-threatening complication of tumor lysis syndrome due to its cardiac arrhythmogenic potential.

Question 185: A 63-year-old male with a 40 pack-year history presents with hemoptysis, weight loss, and a right hilar mass. Biopsy shows small cell lung cancer. Staging workup reveals no distant metastases and disease confined to one hemithorax. What is the standard treatment?

Surgery followed by adjuvant chemotherapy
Immunotherapy with pembrolizumab
Prophylactic cranial irradiation alone
Concurrent cisplatin/etoposide chemotherapy with thoracic radiation (Correct answer)

Correct answer: Concurrent cisplatin/etoposide chemotherapy with thoracic radiation

Limited-stage SCLC is treated with concurrent platinum-based chemotherapy (cisplatin/etoposide) and thoracic radiation, followed by prophylactic cranial irradiation in responders.

Question 186: A patient's labs show: glucose 90 mg/dL, sodium 130 mEq/L, potassium 5.8 mEq/L, bicarbonate 14 mEq/L, and a morning cortisol of 2 mcg/dL. ACTH stimulation test shows a blunted response. Which diagnosis fits?

Conn's syndrome
Cushing's disease
Primary adrenal insufficiency (Addison's disease) (Correct answer)
Secondary adrenal insufficiency

Correct answer: Primary adrenal insufficiency (Addison's disease)

Primary adrenal insufficiency features hyperkalemia (from mineralocorticoid deficiency), hyponatremia, and a blunted cortisol response to ACTH stimulation.

Question 187: Which antibiotic regimen is recommended for outpatient treatment of community-acquired pneumonia in a 45-year-old with no comorbidities and no recent antibiotic use?

Amoxicillin-clavulanate plus azithromycin
Doxycycline monotherapy
Amoxicillin monotherapy (Correct answer)
Levofloxacin monotherapy

Correct answer: Amoxicillin monotherapy

IDSA/ATS guidelines recommend amoxicillin as first-line monotherapy for outpatient CAP in otherwise healthy patients without comorbidities or risk factors for drug-resistant organisms.

Question 188: A patient with celiac disease continues to have diarrhea despite strict gluten avoidance. Repeat small bowel biopsy shows persistent villous atrophy. What complication should be most urgently considered?

Pernicious anemia
Microscopic colitis
Irritable bowel syndrome superimposition
Enteropathy-associated T-cell lymphoma (Correct answer)

Correct answer: Enteropathy-associated T-cell lymphoma

Refractory celiac disease that does not respond to a gluten-free diet raises concern for enteropathy-associated T-cell lymphoma, a serious malignant complication.

Question 189: Pelvic inflammatory disease (PID) is most commonly caused by:

Staphylococcus aureus
Group B Streptococcus
Escherichia coli
Neisseria gonorrhoeae and Chlamydia trachomatis (Correct answer)

Correct answer: Neisseria gonorrhoeae and Chlamydia trachomatis

PID is most commonly polymicrobial but predominantly initiated by sexually transmitted organisms — Neisseria gonorrhoeae and Chlamydia trachomatis.

Question 190: A patient with moderate persistent asthma continues to have frequent exacerbations despite maximum-dose ICS/LABA. IgE is 450 IU/mL and blood eosinophils are 380 cells/μL. Which add-on biologic therapy is most appropriate?

Omalizumab (anti-IgE) (Correct answer)
Dupilumab (anti-IL-4Rα)
Benralizumab (anti-IL-5Rα)
Tezepelumab (anti-TSLP)

Correct answer: Omalizumab (anti-IgE)

Omalizumab is indicated for moderate-to-severe allergic asthma with elevated IgE and sensitivity to perennial allergens when uncontrolled on high-dose ICS/LABA.

Question 191: A 35-year-old woman with sickle cell disease develops sudden chest pain, fever, hypoxia, and a new pulmonary infiltrate during a painful crisis. The most likely diagnosis is:

Lobar pneumonia
Acute chest syndrome (Correct answer)
Pulmonary hypertension
Pulmonary embolism

Correct answer: Acute chest syndrome

Acute chest syndrome (new pulmonary infiltrate + chest symptoms) is the leading cause of death in sickle cell disease and requires exchange transfusion in severe cases.

Question 192: A 48-year-old man presents with fatigue, bronze skin discoloration, elevated liver enzymes, and diabetes. Serum ferritin is 2,800 ng/mL and transferrin saturation is 72%. What is the most likely diagnosis?

Alcoholic hepatitis
Wilson's disease
Hereditary hemochromatosis (Correct answer)
Hemolytic anemia

Correct answer: Hereditary hemochromatosis

Hereditary hemochromatosis (HFE gene mutation) presents with iron overload causing liver disease, diabetes, skin bronzing, and cardiomyopathy; transferrin saturation >45% is a key screening marker.

Question 193: What is the most common cause of primary postpartum hemorrhage (PPH)?

Uterine atony (Correct answer)
Inherited coagulopathy
Genital tract lacerations
Retained placental fragments

Correct answer: Uterine atony

Uterine atony — failure of the uterus to contract after delivery — accounts for approximately 80% of postpartum hemorrhage cases.

Question 194: A patient on lithium therapy develops polyuria and polydipsia. Water deprivation test shows urine does not concentrate even after desmopressin. What is the diagnosis?

Nephrogenic diabetes insipidus (Correct answer)
Central diabetes insipidus
SIADH
Primary polydipsia

Correct answer: Nephrogenic diabetes insipidus

Lithium causes nephrogenic DI by impairing collecting duct response to ADH; urine fails to concentrate despite exogenous desmopressin.

Question 195: A 30-year-old man develops urethritis, conjunctivitis, and asymmetric arthritis after a Chlamydia trachomatis infection. Which HLA type is associated with increased risk?

HLA-B51
HLA-B27 (Correct answer)
HLA-DR3
HLA-DR4

Correct answer: HLA-B27

Reactive arthritis (formerly Reiter syndrome) is strongly associated with HLA-B27 and occurs after genitourinary or gastrointestinal infections.

Question 196: A 50-year-old woman with rheumatoid arthritis develops atlantoaxial instability. Which cervical vertebrae are involved, and what is the primary danger?

C2-C3 instability with vertebral artery injury
C1-C2 instability with risk of spinal cord compression (Correct answer)
C5-C6 instability with nerve root compression
C3-C4 instability with diaphragm paralysis

Correct answer: C1-C2 instability with risk of spinal cord compression

RA-related erosion of the transverse ligament causes C1-C2 (atlantoaxial) instability, risking odontoid process compression of the spinal cord.

Question 197: A 75-year-old man is brought to the emergency department 90 minutes after the sudden onset of left-sided weakness and facial droop. A non-contrast head CT scan shows no evidence of intracranial hemorrhage. His blood pressure is 170/95 mmHg. What is the most appropriate immediate intervention?

Observation and supportive care with repeat CT in 24 hours
Urgent neurosurgical consultation for hematoma evacuation
Administration of intravenous alteplase (tPA) (Correct answer)
Immediate administration of high-dose aspirin

Correct answer: Administration of intravenous alteplase (tPA)

For patients with an acute ischemic stroke who present within the 3 to 4.5-hour therapeutic window and have no contraindications (like hemorrhage on CT), intravenous alteplase (a thrombolytic agent) is the standard of care to restore cerebral blood flow and improve functional outcomes. Aspirin is typically started 24 hours after tPA administration. Neurosurgical consultation would be for a hemorrhagic stroke, not an ischemic one without hemorrhage. Observation alone would miss the critical opportunity for reperfusion therapy.

Question 198: Which finding on methacholine challenge test indicates a positive result for bronchial hyperreactivity?

≥25% increase in airway resistance
≥10% fall in FEV1 at 8 mg/mL concentration
≥20% fall in FEV1 at ≤16 mg/mL (PC20 ≤16 mg/mL) (Correct answer)
≥15% fall in FVC at any concentration

Correct answer: ≥20% fall in FEV1 at ≤16 mg/mL (PC20 ≤16 mg/mL)

A positive methacholine challenge is defined as a ≥20% fall in FEV1 at a provocative concentration ≤16 mg/mL (PC20 ≤16 mg/mL).

Question 199: A 55-year-old man with limited cutaneous systemic sclerosis presents with Raynaud phenomenon, telangiectasias, and pulmonary hypertension. Which antibody is most commonly associated with this subset?

Anti-centromere antibody (Correct answer)
Anti-Scl-70 (topoisomerase I)
Anti-Jo-1
Anti-dsDNA

Correct answer: Anti-centromere antibody

Anti-centromere antibodies are characteristically associated with limited cutaneous systemic sclerosis (formerly CREST syndrome).

Question 200: A patient with polycystic kidney disease asks about the risk to their children. What is the inheritance pattern of autosomal dominant PKD?

Autosomal dominant, 50% risk to each child (Correct answer)
X-linked dominant, 50% risk to sons
Mitochondrial, 100% maternal transmission
Autosomal recessive, 25% risk

Correct answer: Autosomal dominant, 50% risk to each child

ADPKD (PKD1/PKD2 mutations) follows autosomal dominant inheritance with 50% probability of transmission to each offspring.

Question 201: A 30-year-old woman has hundreds of colonic polyps discovered on colonoscopy. Her father died of colon cancer at age 40. Genetic testing reveals an APC gene mutation. She is at greatest risk for which condition?

Familial adenomatous polyposis (Correct answer)
Lynch syndrome
Juvenile polyposis syndrome
Peutz-Jeghers syndrome

Correct answer: Familial adenomatous polyposis

Familial adenomatous polyposis (FAP) is caused by germline APC mutations, producing hundreds to thousands of adenomatous polyps with nearly 100% lifetime colorectal cancer risk if untreated.

Question 202: Which finding on colonoscopy is most characteristic of Crohn's disease compared to ulcerative colitis?

Pseudopolyps
Skip lesions with cobblestoning (Correct answer)
Continuous mucosal involvement from rectum
Crypt abscesses on biopsy

Correct answer: Skip lesions with cobblestoning

Crohn's disease characteristically produces skip lesions with transmural inflammation, cobblestoning of the mucosa, and can affect any segment of the GI tract.

Question 203: A 45-year-old man presents with sudden onset of thunderclap headache reaching maximal intensity within seconds. CT head is negative. What is the next best step?

Start sumatriptan
Discharge with analgesics
MRI brain with contrast
Lumbar puncture for xanthochromia (Correct answer)

Correct answer: Lumbar puncture for xanthochromia

A negative CT with thunderclap headache requires lumbar puncture to detect xanthochromia, indicating subarachnoid hemorrhage.

Question 204: A 35-year-old patient reports episodic headaches, palpitations, and profuse sweating, often accompanied by severe hypertension. A pheochromocytoma is suspected. What is the most appropriate initial biochemical test to establish the diagnosis?

Serum epinephrine and norepinephrine levels.
Plasma free metanephrines. (Correct answer)
Clonidine suppression test.
24-hour urine for vanillylmandelic acid (VMA).

Correct answer: Plasma free metanephrines.

The initial and most sensitive biochemical test for diagnosing pheochromocytoma is the measurement of plasma free metanephrines or 24-hour urinary fractionated metanephrines. Catecholamines (epinephrine and norepinephrine) are released episodically and can have a short half-life, potentially leading to false-negative results if measured between spells. Metanephrines are metabolites of catecholamines and are produced continuously within the tumor, making them a more reliable marker.

Question 205: A 66-year-old man presents with progressive exertional dyspnea, bibasilar crackles, and digital clubbing. CT chest shows bilateral basal-predominant honeycombing and traction bronchiectasis. Pulmonary function tests reveal a restrictive pattern with reduced DLCO. What is the most likely diagnosis?

Hypersensitivity pneumonitis
Cryptogenic organizing pneumonia
Idiopathic pulmonary fibrosis (Correct answer)
Sarcoidosis

Correct answer: Idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) presents in older men with progressive dyspnea, Velcro crackles, clubbing, and CT showing UIP pattern (honeycombing with basal-predominant traction bronchiectasis).

Question 206: Which initial test is most sensitive for diagnosing ectopic pregnancy?

Serum quantitative beta-hCG (Correct answer)
Urine pregnancy test
Diagnostic laparoscopy
Transvaginal ultrasound

Correct answer: Serum quantitative beta-hCG

Serum quantitative beta-hCG is the most sensitive initial test; in ectopic pregnancy, levels typically fail to double every 48 hours as expected in a normal IUP.

Question 207: Which dermatological condition is characterized by erythematous plaques with silvery scales?

Vitiligo
Eczema
Rosacea
Psoriasis (Correct answer)

Correct answer: Psoriasis

Psoriasis is characterized by well-demarcated erythematous plaques covered with silvery-white scales caused by accelerated keratinocyte turnover.

Question 208: A 28-year-old man with hemoglobin SS disease is started on hydroxyurea. Which mechanism accounts for its primary benefit in sickle cell disease?

Blocks sickling by oxidizing HbS
Reduces blood viscosity by decreasing platelet count
Inhibits sickling by chelating calcium
Increases fetal hemoglobin (HbF) production (Correct answer)

Correct answer: Increases fetal hemoglobin (HbF) production

Hydroxyurea induces HbF synthesis, which dilutes HbS within red cells and inhibits polymerization, reducing vaso-occlusive crises.

Question 209: Which of the following is NOT a normal physiologic change during pregnancy?

Decreased glomerular filtration rate (GFR) (Correct answer)
Increased cardiac output by 40-50%
Decreased systemic vascular resistance
Expanded plasma volume by 40-50%

Correct answer: Decreased glomerular filtration rate (GFR)

GFR increases by 40-60% in normal pregnancy due to increased renal plasma flow; a decreased GFR would be abnormal and suggests renal pathology.

Question 210: A patient with type 2 diabetes is started on metformin. Which mechanism best explains its glucose-lowering effect?

Blocks glucose absorption in the small intestine
Increases insulin secretion from beta cells
Increases renal glucose excretion
Inhibits hepatic gluconeogenesis via AMPK activation (Correct answer)

Correct answer: Inhibits hepatic gluconeogenesis via AMPK activation

Metformin primarily activates AMPK in the liver, suppressing gluconeogenesis and reducing hepatic glucose output.

Question 211: A 45-year-old woman undergoes allogeneic stem cell transplant. On day 35, she develops diarrhea, skin rash, and rising bilirubin. What is the most likely complication?

Veno-occlusive disease
Graft failure
Acute graft-versus-host disease (Correct answer)
CMV colitis

Correct answer: Acute graft-versus-host disease

Acute GVHD (typically within 100 days post-transplant) classically affects skin (rash), gut (diarrhea), and liver (hyperbilirubinemia) as donor T cells attack host tissues.

Question 212: A 70-year-old man has a hemoglobin of 8 g/dL, serum ferritin of 800 ng/mL, low TIBC, and elevated ESR. His anemia is most consistent with:

Sideroblastic anemia
Iron deficiency anemia
Hemolytic anemia
Anemia of chronic disease (Correct answer)

Correct answer: Anemia of chronic disease

Anemia of chronic disease features low iron, low TIBC, high ferritin (iron trapped in stores), and normal-to-low reticulocytes due to hepcidin-mediated sequestration.

Question 213: A 60-year-old diabetic presents with painful, rapidly spreading erythema of the scrotum and perineum with crepitus on palpation. CT shows gas in the soft tissues. Which condition is this?

Fournier's gangrene (necrotizing fasciitis) (Correct answer)
Erysipelas
Cellulitis due to Staphylococcus aureus
Bartholin gland abscess

Correct answer: Fournier's gangrene (necrotizing fasciitis)

Fournier's gangrene is a polymicrobial necrotizing fasciitis of the perineum and genitalia, often involving anaerobes producing gas, requiring emergent surgical debridement.

Question 214: A 28-year-old with cystic fibrosis has FEV1 of 40% predicted and is homozygous for F508del mutation. Which targeted therapy is most appropriate?

Elexacaftor/tezacaftor/ivacaftor (ETI) (Correct answer)
Ivacaftor monotherapy
Lumacaftor/ivacaftor
Ataluren

Correct answer: Elexacaftor/tezacaftor/ivacaftor (ETI)

Elexacaftor/tezacaftor/ivacaftor (Trikafta) is the most effective CFTR modulator for F508del homozygous patients, producing the greatest improvement in FEV1 and sweat chloride.

Question 215: A 25-year-old man sustains a knee injury while playing soccer. He reports hearing a 'pop' and has a positive anterior drawer test. Which structure is most likely injured?

Medial collateral ligament
Posterior cruciate ligament
Lateral meniscus
Anterior cruciate ligament (Correct answer)

Correct answer: Anterior cruciate ligament

A positive anterior drawer test (anterior tibial translation on the femur) indicates anterior cruciate ligament (ACL) tear.

Question 216: Which of the following is considered the first-line and most effective treatment for most patients with moderate to severe obstructive sleep apnea (OSA)?

Weight loss and positional therapy
Mandibular advancement device
Uvulopalatopharyngoplasty (UPPP)
Continuous Positive Airway Pressure (CPAP) (Correct answer)

Correct answer: Continuous Positive Airway Pressure (CPAP)

Continuous Positive Airway Pressure (CPAP) therapy is the gold standard and most effective first-line treatment for moderate to severe obstructive sleep apnea. It works by providing a continuous stream of air to keep the airway open during sleep. While mandibular advancement devices, surgery, and lifestyle modifications like weight loss are also treatment options, they are typically considered for mild to moderate OSA or for patients who cannot tolerate CPAP.

Question 217: A 70-year-old presents with progressive gait instability, urinary incontinence, and cognitive decline. MRI shows enlarged ventricles disproportionate to sulcal atrophy. What is the diagnosis?

Vascular dementia
Lewy body dementia
Alzheimer dementia
Normal pressure hydrocephalus (Correct answer)

Correct answer: Normal pressure hydrocephalus

The classic triad of gait apraxia, urinary incontinence, and dementia with ventriculomegaly suggests normal pressure hydrocephalus.

Question 218: A 22-year-old male presents to a sexual health clinic with a two-day history of purulent urethral discharge and dysuria. A Gram stain is performed on a smear of the discharge. Which of the following microscopic findings would be most diagnostic for Neisseria gonorrhoeae infection in this patient?

Gram-negative rods arranged in a 'school of fish' pattern
Gram-negative diplococci located within neutrophils (Correct answer)
Absence of organisms but numerous polymorphonuclear leukocytes
Gram-positive cocci in chains

Correct answer: Gram-negative diplococci located within neutrophils

The classic and highly specific Gram stain finding for urethritis caused by Neisseria gonorrhoeae in a symptomatic male is the presence of gram-negative (pink/red) diplococci (cocci in pairs, often kidney-bean shaped) inside of polymorphonuclear leukocytes (neutrophils). [11, 21, 33] This finding has a high sensitivity (>95%) and specificity (>99%) in this clinical context. [37]

Question 219: A 50-year-old man receiving cisplatin-based chemotherapy develops fatigue with hemoglobin 7.5 g/dL, low reticulocytes, and inappropriately low erythropoietin. The mechanism of his anemia is:

Renal EPO suppression from cisplatin nephrotoxicity (Correct answer)
Bone marrow suppression
Iron deficiency from GI bleeding
Hemolysis

Correct answer: Renal EPO suppression from cisplatin nephrotoxicity

Cisplatin causes nephrotoxicity that impairs renal EPO production, leading to anemia disproportionate to the degree of myelosuppression.

Question 220: A 50-year-old gardener develops a nodular lesion on his hand that spreads up the lymphatics in a linear pattern after a thorn injury. KOH prep shows cigar-shaped yeast at 37°C. Which antifungal is preferred?

Itraconazole (Correct answer)
Fluconazole
Amphotericin B
Griseofulvin

Correct answer: Itraconazole

Sporotrichosis (Sporothrix schenckii) presenting with lymphocutaneous spread is treated with itraconazole; potassium iodide is an alternative for cutaneous disease.

Question 221: The suffix '-phagia' means:

Eating or swallowing (Correct answer)
Breathing
Speaking
Seeing

Correct answer: Eating or swallowing

-Phagia refers to eating or swallowing, as in dysphagia (difficulty swallowing).

Question 222: Stevens-Johnson Syndrome (SJS) is most commonly triggered by:

Autoimmune disease
Viral infections
Drug reactions (Correct answer)
Bacterial toxins

Correct answer: Drug reactions

Stevens-Johnson Syndrome is most commonly triggered by drug reactions, particularly sulfonamides, anticonvulsants, and NSAIDs.

Question 223: A 25-year-old with hematuria and sensorineural hearing loss has a family history of renal failure. Biopsy shows thinning and splitting of the GBM in a 'basket-weave' pattern. What is the diagnosis?

IgA nephropathy
Alport syndrome (Correct answer)
Anti-GBM disease
Thin basement membrane disease

Correct answer: Alport syndrome

Alport syndrome (X-linked, COL4A5 mutation) presents with hematuria, sensorineural deafness, and ocular abnormalities with characteristic GBM lamellation on EM.

Question 224: A 45-year-old woman presents with bilateral wrist pain, swan-neck deformities, and positive anti-CCP antibodies. Which mechanism best explains joint destruction in her condition?

Bacterial seeding of the joint space
Calcium pyrophosphate deposition in cartilage
Pannus formation eroding cartilage and bone (Correct answer)
Urate crystal deposition in synovial fluid

Correct answer: Pannus formation eroding cartilage and bone

Rheumatoid arthritis causes pannus (proliferative synovial tissue) that invades and destroys cartilage and subchondral bone.

Question 225: Which sleep disorder is most strongly associated with systemic hypertension, atrial fibrillation, and increased cardiovascular mortality?

Narcolepsy
Obstructive sleep apnea (Correct answer)
Obesity hypoventilation syndrome
Central sleep apnea

Correct answer: Obstructive sleep apnea

Obstructive sleep apnea is independently associated with hypertension, atrial fibrillation, stroke, and cardiovascular mortality through intermittent hypoxia and sympathetic activation.

Question 226: A patient with a large left-sided pleural effusion undergoes thoracentesis. After removal of 1.2 L, the patient develops acute chest tightness and CT shows ipsilateral pulmonary infiltrates. What is the most likely complication?

Tension pneumothorax
Re-expansion pulmonary edema (Correct answer)
Paradoxical embolism
Hemothorax from intercostal vessel injury

Correct answer: Re-expansion pulmonary edema

Re-expansion pulmonary edema is a rare but serious complication of rapid large-volume thoracentesis, caused by rapid re-expansion of the collapsed lung.

Question 227: A 35-year-old woman with diffuse systemic sclerosis develops progressive dyspnea. High-resolution CT shows basal-predominant ground-glass opacities and honeycombing. Which antibody is most associated with this pulmonary complication?

Anti-Jo-1
Anti-U1 RNP
Anti-centromere
Anti-Scl-70 (anti-topoisomerase I) (Correct answer)

Correct answer: Anti-Scl-70 (anti-topoisomerase I)

Anti-Scl-70 antibodies are associated with diffuse cutaneous systemic sclerosis and a higher risk of interstitial lung disease.

Question 228: What does 'leukocytosis' mean?

Increase in platelets
Decrease in white blood cells
Decrease in red blood cells
Increase in white blood cells (Correct answer)

Correct answer: Increase in white blood cells

Leuko- (white) + cyto- (cell) + -osis (abnormal increase) = abnormal increase in white blood cells.

Question 229: A patient with multiple myeloma shows a serum M-spike on SPEP. Which immunoglobulin heavy chain is most commonly involved in multiple myeloma?

IgD
IgM
IgG (Correct answer)
IgA

Correct answer: IgG

IgG myeloma is the most common subtype, accounting for approximately 50–60% of multiple myeloma cases.

Question 230: A 28-year-old woman presents with amenorrhea, galactorrhea, and a serum prolactin of 120 ng/mL. MRI shows a 12 mm pituitary lesion. What is the first-line treatment?

Radiation therapy
Dopamine agonist (cabergoline) (Correct answer)
Transsphenoidal surgery
Bromocriptine + surgery combination

Correct answer: Dopamine agonist (cabergoline)

Dopamine agonists such as cabergoline are the first-line treatment for macroprolactinomas, effectively shrinking the tumor and normalizing prolactin.

Question 231: A 42-year-old female presents with central obesity, purple striae, hypertension, and easy bruising. You suspect Cushing's syndrome. Which of the following is considered a first-line screening test to confirm hypercortisolism?

High-dose dexamethasone suppression test.
24-hour urinary free cortisol measurement. (Correct answer)
Plasma ACTH level.
Abdominal MRI.

Correct answer: 24-hour urinary free cortisol measurement.

First-line screening tests for Cushing's syndrome aim to document endogenous hypercortisolism. The three accepted initial tests are the 24-hour urinary free cortisol (UFC), the late-night salivary cortisol, and the 1-mg overnight dexamethasone suppression test. A plasma ACTH level and a high-dose dexamethasone suppression test are second-line tests used to determine the *cause* of Cushing's syndrome (i.e., pituitary vs. adrenal vs. ectopic) after hypercortisolism has been confirmed. Imaging is performed only after biochemical confirmation.

Question 232: A 72-year-old male with end-stage renal disease presents to the ER with severe weakness and palpitations. An ECG shows peaked T waves and a widened QRS complex. His serum potassium is 7.2 mEq/L. What is the most appropriate initial step in management to stabilize the cardiac membrane?

Administer intravenous sodium bicarbonate.
Arrange for emergent hemodialysis.
Administer intravenous calcium gluconate. (Correct answer)
Administer intravenous regular insulin and glucose.

Correct answer: Administer intravenous calcium gluconate.

In a patient with severe hyperkalemia and ECG changes, the immediate priority is to stabilize the cardiac membrane to prevent life-threatening arrhythmias. Intravenous calcium gluconate (or calcium chloride) directly antagonizes the membrane-depolarizing effects of hyperkalemia without lowering the serum potassium level. While insulin/glucose, sodium bicarbonate, and hemodialysis are all crucial for lowering total body potassium, they act more slowly and do not provide immediate cardioprotection.

Question 233: A 70-year-old man with a history of smoking and alcohol use presents with progressive dysphagia and a mid-esophageal mass. Biopsy shows squamous cell carcinoma. Which statement is true regarding this tumor?

It is associated with Barrett's metaplasia
It is most common in the middle and upper thirds of the esophagus (Correct answer)
It arises most commonly in the lower third of the esophagus
It has a better prognosis than esophageal adenocarcinoma

Correct answer: It is most common in the middle and upper thirds of the esophagus

Squamous cell carcinoma of the esophagus typically arises in the middle and upper thirds and is associated with smoking, alcohol, achalasia, and hot beverage consumption.

Question 234: A 45-year-old man with a history of alcohol abuse is brought to the emergency department. He has been continuously seizing for 10 minutes despite pre-hospital administration of an IM benzodiazepine. In the ED, he remains unresponsive and continues to have generalized tonic-clonic seizure activity. After securing the airway and obtaining IV access, which medication should be administered first?

An intravenous bolus of lorazepam (Correct answer)
A loading dose of oral phenytoin
An intravenous bolus of propofol
An intravenous infusion of phenobarbital

Correct answer: An intravenous bolus of lorazepam

The first-line emergent treatment for status epilepticus is an intravenous benzodiazepine. Lorazepam is often preferred due to its rapid onset and relatively longer duration of action compared to diazepam. If seizure activity continues after adequate benzodiazepine administration, a second-line agent like fosphenytoin, levetiracetam, or valproic acid would be used. Propofol and phenobarbital are generally reserved for refractory status epilepticus that has not responded to first and second-line agents. Oral medications are not appropriate for emergent management.

Question 235: A 25-year-old presents with bloody diarrhea 4 days after attending a barbecue. Stool culture grows E. coli O157:H7. Which complication is most feared in this patient?

Pseudomembranous colitis
Toxic megacolon
Intussusception
Hemolytic uremic syndrome (Correct answer)

Correct answer: Hemolytic uremic syndrome

E. coli O157:H7 produces Shiga toxin that damages renal endothelium, causing hemolytic uremic syndrome characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure.

Question 236: A 62-year-old male is undergoing surveillance after a curative resection for Stage III colon cancer one year ago. Which of the following tumor markers is most appropriate to monitor for disease recurrence in this patient?

Alpha-fetoprotein (AFP)
Prostate-specific antigen (PSA)
CA 19-9
Carcinoembryonic antigen (CEA) (Correct answer)

Correct answer: Carcinoembryonic antigen (CEA)

Carcinoembryonic antigen (CEA) is the standard tumor marker used for surveillance in patients with a history of colorectal cancer after curative treatment. A rising CEA level on serial testing can be the first sign of disease recurrence and should prompt further imaging and investigation. CA 19-9 is associated with pancreatic cancer, AFP with hepatocellular carcinoma and certain germ cell tumors, and PSA with prostate cancer.

Question 237: A 28-year-old woman presents with cyclic pelvic pain, dysmenorrhea, dyspareunia, and infertility. The most likely diagnosis is:

Uterine leiomyomas (fibroids)
Polycystic ovarian syndrome
Endometriosis (Correct answer)
Cervical stenosis

Correct answer: Endometriosis

The classic triad of dysmenorrhea, dyspareunia, and infertility in a reproductive-age woman strongly suggests endometriosis caused by ectopic endometrial implants.

Question 238: The most critical initial step in managing toxic epidermal necrolysis (TEN) is:

Systemic broad-spectrum antibiotics
Immediate IVIG infusion
Discontinue the offending drug and transfer to a burn unit (Correct answer)
High-dose IV corticosteroids

Correct answer: Discontinue the offending drug and transfer to a burn unit

Immediate discontinuation of the causative drug followed by supportive care in a specialized burn unit is the cornerstone of TEN management.

Question 239: A 10-year-old girl has hyperextensible skin, hypermobile joints, and easy bruising. Skin biopsy shows abnormal collagen cross-linking. She likely has a defect in which enzyme?

Prolyl hydroxylase
Lysyl hydroxylase
Lysyl oxidase (Correct answer)
Collagenase

Correct answer: Lysyl oxidase

Ehlers-Danlos syndrome (classical type) involves defective lysyl oxidase or collagen genes, impairing collagen cross-linking and resulting in skin and joint laxity.

Question 240: A patient with nephrotic syndrome has a serum albumin of 1.8 g/dL. Which complication is most directly caused by hypoalbuminemia?

Metabolic alkalosis
Edema from reduced oncotic pressure (Correct answer)
Hypertension from sodium retention
Hyperkalemia

Correct answer: Edema from reduced oncotic pressure

Hypoalbuminemia reduces plasma oncotic pressure, allowing fluid to shift into the interstitium and causing edema.

Question 241: A 72-year-old woman develops acute aortic regurgitation after bacterial endocarditis. Why does she develop acute pulmonary edema while a patient with chronic aortic regurgitation is compensated?

Acute AR causes higher systemic vascular resistance
Bacterial toxins directly depress myocardial contractility
Acute AR causes more severe mitral regurgitation
The unprepared left ventricle cannot accommodate the sudden volume load (Correct answer)

Correct answer: The unprepared left ventricle cannot accommodate the sudden volume load

In acute AR, the normal-sized left ventricle has poor compliance and cannot accommodate the sudden regurgitant volume, causing abrupt elevation in LV end-diastolic pressure and pulmonary edema.

Question 242: A 55-year-old with HIV presents with focal neurological deficits. MRI shows multiple ring-enhancing lesions. Toxoplasma serology is negative. What diagnosis must be excluded?

Primary CNS lymphoma (Correct answer)
Glioblastoma multiforme
Bacterial brain abscess
Metastatic carcinoma

Correct answer: Primary CNS lymphoma

In HIV patients with negative toxoplasma serology, primary CNS lymphoma is the leading differential for ring-enhancing lesions.

Question 243: What does the prefix 'brady-' mean?

Slow (Correct answer)
Double
Fast
Absent

Correct answer: Slow

Brady- means slow, as in bradycardia (slow heart rate).

Question 244: First-line treatment for PCOS with irregular menses when pregnancy is NOT desired is:

Gonadotropin injections
Metformin alone
Clomiphene citrate
Combined oral contraceptive pills (Correct answer)

Correct answer: Combined oral contraceptive pills

Combined oral contraceptives are first-line therapy for menstrual irregularity in PCOS, reducing LH-driven androgen production and regulating cycle length.

Question 245: Which of the following histopathological findings is most characteristic of Crohn's disease and helps differentiate it from ulcerative colitis?

Crypt abscesses
Continuous inflammation limited to the mucosa
Non-caseating granulomas (Correct answer)
Pseudopolyps

Correct answer: Non-caseating granulomas

Non-caseating granulomas are a hallmark of Crohn's disease, found in a significant number of cases, and are not seen in ulcerative colitis. Their presence points to the transmural, granulomatous inflammation characteristic of Crohn's. Crypt abscesses and pseudopolyps can be seen in both conditions but are more typical of ulcerative colitis. Continuous inflammation limited to the mucosa is the classic description for ulcerative colitis, whereas Crohn's disease is characterized by discontinuous (skip lesions) and transmural inflammation.

Question 246: A 30-year-old woman presents with intermittent diplopia, ptosis worsening through the day, and proximal limb weakness. Ice pack test improves ptosis. What antibody should be ordered first?

Anti-voltage-gated calcium channel
Anti-LGI1
Anti-AChR (Correct answer)
Anti-MuSK

Correct answer: Anti-AChR

Anti-acetylcholine receptor (AChR) antibodies are positive in ~85% of generalized myasthenia gravis cases and are the first-line test.

Question 247: A patient presents with malar rash, joint pain, and positive ANA. The most likely diagnosis is:

Lyme disease
Psoriatic arthritis
Systemic lupus erythematosus (Correct answer)
Rheumatoid arthritis

Correct answer: Systemic lupus erythematosus

The combination of malar (butterfly) rash, arthritis, and positive ANA is classic for systemic lupus erythematosus (SLE).

Question 248: A 25-year-old woman presents with new-onset focal-onset impaired awareness seizures. MRI shows a unilateral medial temporal sclerosis. What is the most likely seizure type?

Juvenile myoclonic epilepsy
Lennox-Gastaut syndrome
Absence epilepsy
Mesial temporal lobe epilepsy (Correct answer)

Correct answer: Mesial temporal lobe epilepsy

Hippocampal sclerosis is the hallmark of mesial temporal lobe epilepsy, the most common focal epilepsy syndrome in adults.

Question 249: A 22-year-old college student presents with fever, severe headache, photophobia, and neck stiffness. CSF shows WBC 2,000 (90% PMNs), low glucose, high protein. What is empiric treatment?

Doxycycline
Ceftriaxone + vancomycin + dexamethasone (Correct answer)
Amphotericin B
Acyclovir alone

Correct answer: Ceftriaxone + vancomycin + dexamethasone

Bacterial meningitis is treated empirically with ceftriaxone plus vancomycin (for resistant pneumococcus) and dexamethasone to reduce inflammation.

Question 250: A 50-year-old man with alcoholic liver disease presents with confusion and asterixis. Labs show elevated ammonia. Which dietary modification is most appropriate?

High-fat, low-carbohydrate diet
Moderate protein intake with preference for branched-chain amino acids (Correct answer)
Eliminate all protein intake
Restrict sodium to <2 g/day

Correct answer: Moderate protein intake with preference for branched-chain amino acids

Hepatic encephalopathy patients should receive adequate protein (preferably plant-based or branched-chain amino acids) rather than protein restriction, which worsens sarcopenia and outcomes.

Question 251: Which finding on urinalysis is most consistent with acute tubular necrosis?

Oval fat bodies
RBC casts
WBC casts
Muddy brown granular casts (Correct answer)

Correct answer: Muddy brown granular casts

ATN causes sloughing of tubular epithelial cells that form muddy brown granular casts, which are pathognomonic for this condition.

Question 252: Which staging system is used for Hodgkin lymphoma and defines Stage III as involvement of lymph node regions on both sides of the diaphragm?

Rai staging
Ann Arbor staging (Correct answer)
Binet staging
FLIPI scoring

Correct answer: Ann Arbor staging

The Ann Arbor staging system (with Cotswolds modification) classifies Hodgkin and non-Hodgkin lymphomas; Stage III involves nodes on both sides of the diaphragm.

Question 253: A patient with idiopathic pulmonary fibrosis (IPF) shows progressive decline in FVC. Which medication has been shown to slow disease progression?

Nintedanib (Correct answer)
Prednisone
Azathioprine
N-acetylcysteine

Correct answer: Nintedanib

Nintedanib and pirfenidone are the only antifibrotic agents proven to slow FVC decline in IPF; prednisone and azathioprine are no longer recommended.

Question 254: A 70-year-old smoker presents with new-onset hemoptysis. CT shows a 3.5 cm spiculated right upper lobe mass. PET scan shows no distant metastases. Mediastinoscopy shows no lymph node involvement. What is the preferred treatment?

Lobectomy (Correct answer)
Definitive chemoradiation
Wedge resection
Stereotactic body radiation therapy (SBRT)

Correct answer: Lobectomy

Lobectomy is the preferred surgical approach for stage I-II non-small cell lung cancer in patients with adequate pulmonary reserve.

Question 255: A 68-year-old male with small cell lung cancer is admitted with confusion and lethargy. His laboratory results are significant for a serum sodium of 118 mEq/L. Which of the following laboratory patterns is most consistent with the Syndrome of Inappropriate Antidiuretic Hormone (SIADH)?

Euvolemic hyponatremia, low urine osmolality (<100 mOsm/kg), high urine sodium (>40 mEq/L).
Hypervolemic hyponatremia, low urine osmolality (<100 mOsm/kg), low urine sodium (<20 mEq/L).
Hypovolemic hyponatremia, high urine osmolality (>450 mOsm/kg), low urine sodium (<20 mEq/L).
Euvolemic hyponatremia, high urine osmolality (>100 mOsm/kg), high urine sodium (>40 mEq/L). (Correct answer)

Correct answer: Euvolemic hyponatremia, high urine osmolality (>100 mOsm/kg), high urine sodium (>40 mEq/L).

The key features of SIADH are euvolemic hyponatremia due to excess free water retention. Despite the low serum osmolality, the urine is inappropriately concentrated (urine osmolality >100 mOsm/kg). The body attempts to excrete the excess fluid by promoting natriuresis, leading to a high urine sodium concentration (typically >40 mEq/L).

Question 256: What is the most common gynecologic malignancy in the United States?

Vulvar cancer
Endometrial (uterine) cancer (Correct answer)
Cervical cancer
Ovarian cancer

Correct answer: Endometrial (uterine) cancer

Endometrial cancer is the most common gynecologic malignancy in the US, typically presenting with postmenopausal uterine bleeding.

Question 257: Which of the following is the fundamental pathogenic mechanism underlying Myasthenia Gravis?

Deposition of alpha-synuclein aggregates in motor neurons
T-cell mediated attack on the myelin sheath of peripheral nerves
Antibody-mediated destruction of postsynaptic acetylcholine receptors (Correct answer)
Degeneration of upper and lower motor neurons

Correct answer: Antibody-mediated destruction of postsynaptic acetylcholine receptors

Myasthenia Gravis is an autoimmune disorder characterized by the production of antibodies against components of the postsynaptic membrane at the neuromuscular junction, most commonly the nicotinic acetylcholine receptor (AChR). This leads to a reduced number of functional receptors, impairing neuromuscular transmission and causing fluctuating muscle weakness. Motor neuron degeneration is the basis of Amyotrophic Lateral Sclerosis (ALS). T-cell mediated attack on peripheral myelin is characteristic of Guillain-Barré syndrome. Alpha-synuclein is associated with Parkinson's disease.

Question 258: A patient with longstanding type 2 diabetes presents with distal symmetric burning pain and loss of vibration sense in the feet. Which pathway is primarily damaged?

Corticospinal tract
Anterior spinothalamic tract
Dorsal columns and small unmyelinated C-fibers (Correct answer)
Spinocerebellar tract

Correct answer: Dorsal columns and small unmyelinated C-fibers

Diabetic peripheral neuropathy affects both small fibers (pain/temperature, C-fibers) and large fibers (vibration, dorsal column) in a length-dependent pattern.

Question 259: A 35-year-old woman presents with chronic watery diarrhea, flushing, and wheezing. Urine 5-HIAA is elevated. CT abdomen shows liver metastases. What is the most likely primary tumor site?

Pancreas
Stomach
Small intestine (Correct answer)
Lung

Correct answer: Small intestine

Carcinoid tumors most commonly arise in the small intestine (ileum) and cause carcinoid syndrome only after metastasizing to the liver, bypassing first-pass metabolism of serotonin.

Question 260: A 40-year-old presents with behavioral disinhibition, hyperphagia, and executive dysfunction with preserved memory. MRI shows frontal and anterior temporal atrophy. What is the diagnosis?

Creutzfeldt-Jakob disease
Huntington disease
Alzheimer disease
Frontotemporal dementia (Correct answer)

Correct answer: Frontotemporal dementia

Behavioral variant frontotemporal dementia is characterized by frontal lobe disinhibition, hyperphagia, and executive dysfunction with relatively preserved memory.

Question 261: A 72-year-old patient is being evaluated for suspected idiopathic pulmonary fibrosis (IPF). Which of the following findings on high-resolution computed tomography (HRCT) of the chest is most characteristic of a 'definite UIP' (Usual Interstitial Pneumonia) pattern, often allowing for a confident diagnosis of IPF without a lung biopsy?

Peribronchovascular-centered reticulation with sparing of the subpleural lung.
Widespread consolidation and pleural effusions.
Predominantly upper lobe ground-glass opacities and micronodules.
Subpleural, basal predominant honeycombing and traction bronchiectasis. (Correct answer)

Correct answer: Subpleural, basal predominant honeycombing and traction bronchiectasis.

The hallmark of a definite Usual Interstitial Pneumonia (UIP) pattern on HRCT, which is the radiologic signature of IPF, is the presence of subpleural and basal predominant reticular abnormalities, honeycombing, and traction bronchiectasis. The other patterns described are inconsistent with a UIP pattern and suggest alternative diagnoses.

Question 262: A 35-year-old woman develops fever, dysuria, flank pain, and costovertebral angle tenderness. Urine culture grows >100,000 CFU/mL of a gram-negative rod that is oxidase-negative and ferments lactose. Which organism?

Klebsiella pneumoniae
Proteus mirabilis
Pseudomonas aeruginosa
Escherichia coli (Correct answer)

Correct answer: Escherichia coli

E. coli is the most common cause of uncomplicated pyelonephritis, fermenting lactose (pink colonies on MacConkey agar) and being oxidase-negative, with the P fimbriae mediating renal tropism.

Question 263: A 35-year-old woman with primary sclerosing cholangitis (PSC) is found to have concurrent inflammatory bowel disease. Which IBD pattern is most classically associated with PSC?

Crohn's disease with perianal involvement
Ulcerative colitis with backwash ileitis (Correct answer)
Microscopic colitis
Ischemic colitis

Correct answer: Ulcerative colitis with backwash ileitis

Primary sclerosing cholangitis is most strongly associated with ulcerative colitis, particularly pancolitis with backwash ileitis, occurring in up to 90% of PSC patients who have IBD.

Question 264: Which skin finding is pathognomonic for early Lyme disease?

Target lesions (erythema multiforme)
Petechial purpuric rash
Erythema migrans (Correct answer)
Vesicular eruption on dermatomal distribution

Correct answer: Erythema migrans

Erythema migrans — an expanding annular rash with central clearing at the Ixodes tick bite site — is pathognomonic for Lyme disease caused by Borrelia burgdorferi.

Question 265: A patient with acute leukemia develops a prolonged PT, aPTT, low fibrinogen, elevated D-dimer, and thrombocytopenia. Which leukemia subtype is classically associated with this coagulopathy?

AML-M2 (with t(8;21))
ALL (B-cell)
CML blast crisis
AML-M3 (APL with t(15;17)) (Correct answer)

Correct answer: AML-M3 (APL with t(15;17))

Acute promyelocytic leukemia (APL/AML-M3) releases procoagulants from granules causing DIC; ATRA is urgently needed before cytotoxic chemotherapy.

Question 266: A 19-year-old woman has a BMI of 16.5, self-induced vomiting after eating, and an intense fear of weight gain despite being significantly underweight. She has secondary amenorrhea. What is the most likely diagnosis?

Avoidant/restrictive food intake disorder
Bulimia nervosa
Anorexia nervosa, binge-eating/purging subtype (Correct answer)
Binge eating disorder

Correct answer: Anorexia nervosa, binge-eating/purging subtype

Anorexia nervosa (binge-eating/purging subtype) is defined by significantly low body weight plus purging behaviors; the critically low BMI distinguishes it from bulimia nervosa, where patients are typically normal weight.

Question 267: A 58-year-old with COPD has an FEV1/FVC ratio of 0.62 and FEV1 of 48% predicted. He remains symptomatic on LABA monotherapy. What is the most appropriate next step?

Add long-acting muscarinic antagonist (LAMA) (Correct answer)
Start oral theophylline
Initiate roflumilast
Add inhaled corticosteroid (ICS)

Correct answer: Add long-acting muscarinic antagonist (LAMA)

GOLD guidelines recommend dual bronchodilation (LABA + LAMA) for COPD patients symptomatic on monotherapy before adding ICS.

Question 268: A 68-year-old male with a significant smoking history presents with increased dyspnea, cough, and sputum production. His baseline is managed with a LAMA/LABA inhaler. He has had two moderate exacerbations in the past year. According to the most recent GOLD guidelines, what is the most appropriate next step in managing his stable COPD?

Prescribe a daily macrolide antibiotic.
Add an inhaled corticosteroid (ICS) to his current regimen. (Correct answer)
Switch to a short-acting beta-agonist (SABA) as needed.
Initiate long-term oral corticosteroid therapy.

Correct answer: Add an inhaled corticosteroid (ICS) to his current regimen.

According to the GOLD 2024 report, for a patient with persistent exacerbations on LAMA/LABA therapy, particularly with a history of ≥2 moderate exacerbations in the last year, the next step is to add an inhaled corticosteroid (ICS), creating a triple therapy regimen (LAMA/LABA/ICS). SABA is for rescue use, not maintenance. Long-term oral corticosteroids have significant side effects and are not recommended for stable management. Daily macrolides are considered for former smokers with persistent exacerbations but after triple therapy has been optimized.

Question 269: Which ultraviolet radiation type is most strongly associated with melanoma development?

UVC (100-290 nm)
UVB (290-320 nm)
UVA (320-400 nm) (Correct answer)
Infrared radiation

Correct answer: UVA (320-400 nm)

UVA radiation penetrates deeply into the dermis and is primarily associated with melanoma through indirect oxidative DNA damage.

Question 270: A 70-year-old man presents with confusion, polyuria, and blood glucose of 950 mg/dL. Serum bicarbonate is 22 mEq/L and ketones are negative. What is the diagnosis?

Alcoholic ketoacidosis
Hyperosmolar hyperglycemic state (HHS) (Correct answer)
Lactic acidosis
Diabetic ketoacidosis

Correct answer: Hyperosmolar hyperglycemic state (HHS)

HHS presents with extreme hyperglycemia and hyperosmolarity without significant ketoacidosis, typically in elderly type 2 diabetics.

Question 271: A 10-year-old boy presents with recurrent episodes of painful, swollen joints (hemarthrosis), particularly in his knees and ankles, after minor trauma. His laboratory studies show a prolonged activated partial thromboplastin time (aPTT) that corrects with a mixing study, a normal prothrombin time (PT), and a normal platelet count. Which of the following is the most likely diagnosis?

Disseminated intravascular coagulation (DIC)
Hemophilia A (Correct answer)
Von Willebrand disease (Type 1)
Vitamin K deficiency

Correct answer: Hemophilia A

The clinical presentation of spontaneous hemarthrosis in a male patient, combined with an isolated prolonged aPTT, is classic for Hemophilia A (Factor VIII deficiency) or Hemophilia B (Factor IX deficiency). The aPTT measures the integrity of the intrinsic pathway, which includes Factor VIII. A normal PT and platelet count make DIC and Vitamin K deficiency (which would prolong PT first) less likely. While Von Willebrand disease can sometimes present with a prolonged aPTT due to low Factor VIII levels, it is primarily a disorder of platelet adhesion, typically causing mucocutaneous bleeding rather than deep joint bleeds.

Question 272: Which segment of the nephron is impermeable to water under all conditions, even in the presence of ADH?

Descending limb of loop of Henle
Collecting duct
Thick ascending limb of loop of Henle (Correct answer)
Proximal convoluted tubule

Correct answer: Thick ascending limb of loop of Henle

The thick ascending limb is constitutively impermeable to water, allowing it to dilute tubular fluid regardless of ADH levels.

Question 273: A patient with Cushing's syndrome undergoes a high-dose dexamethasone suppression test and cortisol is suppressed by >50%. What is the most likely source of excess cortisol?

Pituitary corticotroph adenoma (Cushing's disease) (Correct answer)
Ectopic ACTH-secreting tumor
Adrenal adenoma
Adrenal carcinoma

Correct answer: Pituitary corticotroph adenoma (Cushing's disease)

Suppression of cortisol with high-dose but not low-dose dexamethasone indicates a pituitary source (Cushing's disease), as the adenoma retains partial feedback sensitivity.

Question 274: What is the most common cause of first-trimester spontaneous abortion?

Antiphospholipid syndrome
Chromosomal abnormalities (Correct answer)
Uterine anomalies
Cervical incompetence

Correct answer: Chromosomal abnormalities

Chromosomal abnormalities, most commonly trisomies due to meiotic non-disjunction, account for approximately 50-60% of first-trimester spontaneous abortions.

Question 275: A 50-year-old woman with rheumatoid arthritis develops a vasculitic rash, peripheral neuropathy, and digital gangrene. Which complication of RA does she have?

Sjögren overlap syndrome
Felty syndrome
Caplan syndrome
Rheumatoid vasculitis (Correct answer)

Correct answer: Rheumatoid vasculitis

Rheumatoid vasculitis is a rare but serious extra-articular complication of severe RA characterized by inflammation of small-to-medium vessels causing neuropathy, skin ulcers, and digital ischemia.

Question 276: Which glomerular disease is associated with Heymann nephritis in rats and is the most common cause of nephrotic syndrome in adults?

Membranoproliferative GN
Focal segmental glomerulosclerosis
Membranous nephropathy (Correct answer)
Minimal change disease

Correct answer: Membranous nephropathy

Membranous nephropathy, caused by anti-PLA2R antibodies forming subepithelial immune complexes, is the leading cause of nephrotic syndrome in non-diabetic adults.

Question 277: A 25-year-old man presents with auditory hallucinations, disorganized speech, and flat affect for 8 months. He has no history of substance abuse or medical illness. What is the most appropriate first-line pharmacological treatment?

Clozapine
Haloperidol
Lithium
Risperidone (Correct answer)

Correct answer: Risperidone

Atypical antipsychotics such as risperidone are the first-line treatment for schizophrenia due to their efficacy and lower risk of extrapyramidal side effects compared to typical antipsychotics.

Question 278: A 60-year-old presents with resting tremor, bradykinesia, and cogwheel rigidity. He also has orthostatic hypotension, REM sleep behavior disorder, and anosmia. What is the unifying diagnosis?

Essential tremor
Multiple system atrophy
Parkinson disease (Correct answer)
Drug-induced parkinsonism

Correct answer: Parkinson disease

The combination of motor parkinsonism with autonomic dysfunction, REM sleep behavior disorder, and anosmia is characteristic of Parkinson disease.

Question 279: A 35-year-old man with a history of intravenous drug use presents to the emergency department with a 2-day history of severe right knee pain, swelling, and an inability to bear weight. On examination, the knee is erythematous, warm, and exquisitely tender. He has a fever of 39.0°C (102.2°F). What is the most crucial next step in the diagnosis and management of this patient?

Order blood cultures and C-reactive protein
Initiate empiric intravenous antibiotics
Perform an immediate arthrocentesis (Correct answer)
Obtain an MRI of the knee

Correct answer: Perform an immediate arthrocentesis

The clinical presentation is highly suggestive of septic arthritis, which is a medical emergency requiring prompt diagnosis to prevent joint destruction. The most critical step is to perform an immediate joint aspiration (arthrocentesis). Analysis of the synovial fluid for cell count, Gram stain, and culture is essential to confirm the diagnosis and guide antibiotic therapy. While antibiotics, blood cultures, and imaging are all important, confirming the diagnosis via arthrocentesis is the highest priority and should ideally be done before starting antibiotics.

MD Licensing Exam

The MD Licensing Exam assesses physician competency across core clinical disciplines including cardiovascular, pulmonary, renal, gastrointestinal, neurology, endocrinology, musculoskeletal, hematology, infectious disease, dermatology, and obstetrics.

280

Questions

480 min

Time Limit

75%

To Pass

Checking for saved progress...

Exam Rules

You can skip questions and return to them later
Flag questions for review before submitting
No feedback shown until you submit the entire exam
Unanswered questions count as wrong — answer everything
10 pretest questions are mixed in and don't affect your score
Timer auto-submits when time runs out
Your progress is auto-saved every 30 seconds