Physician Assistant Clinical Knowledge 3 — Questions and Answers
Question 1: A 28-year-old female presents with malar rash, arthritis, and proteinuria. ANA is positive at 1:640. Which antibody is most specific for systemic lupus erythematosus (SLE)?
- Anti-SSA (Ro)
- Anti-Smith (Sm) (Correct answer)
- Anti-histone
- Anti-Scl-70
Correct answer: Anti-Smith (Sm)
Anti-Smith (anti-Sm) antibodies are highly specific for SLE, though not sensitive, making them useful when positive.
Question 2: A 50-year-old man presents with dysphagia to solids and liquids simultaneously from onset. Barium swallow shows a 'bird-beak' appearance. What is the most likely diagnosis?
- Esophageal carcinoma
- Achalasia (Correct answer)
- Diffuse esophageal spasm
- Zenker's diverticulum
Correct answer: Achalasia
Achalasia presents with dysphagia to both solids and liquids from the start due to failure of LES relaxation, and the bird-beak appearance is classic on barium swallow.
Question 3: A neonate presents at 24 hours of life with bilious vomiting. Abdominal X-ray shows a 'double bubble' sign. What is the most likely diagnosis?
- Pyloric stenosis
- Duodenal atresia (Correct answer)
- Hirschsprung's disease
- Meconium ileus
Correct answer: Duodenal atresia
The double bubble sign on X-ray (air in stomach and proximal duodenum) is pathognomonic for duodenal atresia.
Question 4: A 65-year-old smoker presents with hemoptysis, weight loss, and a central lung mass. Serum sodium is 120 mEq/L. Which paraneoplastic syndrome is most likely?
- Cushing's syndrome from ACTH secretion
- Hypercalcemia from PTHrP secretion
- SIADH from ADH secretion (Correct answer)
- Eaton-Lambert syndrome
Correct answer: SIADH from ADH secretion
Small cell lung cancer most commonly produces SIADH via ectopic ADH secretion, causing hyponatremia.
Question 5: A 30-year-old woman at 32 weeks gestation presents with BP 160/110, 3+ proteinuria, and headache. Labs show platelets 85,000/µL, AST 180 U/L, and hemolytic anemia. What is the diagnosis?
- Severe preeclampsia
- HELLP syndrome (Correct answer)
- Thrombotic thrombocytopenic purpura
- Acute fatty liver of pregnancy
Correct answer: HELLP syndrome
HELLP syndrome is defined by Hemolysis, Elevated Liver enzymes, and Low Platelets, and is a severe complication of preeclampsia.
Question 6: A 40-year-old male presents with episodic hypertension, diaphoresis, and palpitations. 24-hour urine shows elevated metanephrines and catecholamines. What is the next best imaging study?
- CT chest
- MRI adrenals without contrast
- CT abdomen/pelvis with contrast (Correct answer)
- Nuclear medicine MIBG scan
Correct answer: CT abdomen/pelvis with contrast
CT abdomen/pelvis with contrast is the first-line imaging for pheochromocytoma after biochemical confirmation to localize the tumor.
Question 7: Which finding best distinguishes Crohn's disease from ulcerative colitis?
- Bloody diarrhea
- Abdominal cramping
- Skip lesions with transmural inflammation (Correct answer)
- Elevated ESR
Correct answer: Skip lesions with transmural inflammation
Crohn's disease is characterized by skip lesions, transmural inflammation, and can involve any part of the GI tract from mouth to anus.
Physician Assistant Clinical Knowledge 3
A 28-year-old female presents with malar rash, arthritis, and proteinuria.
ANA is positive at 1:640.
Which antibody is most specific for systemic lupus erythematosus (SLE)?