ECFMG Medical Knowledge & Clinical Science 5 — Questions and Answers
Question 1: A 25-year-old woman presents with episodic pallor followed by cyanosis then rubor of her fingers triggered by cold. Which condition is this MOST characteristic of?
- Buerger's disease
- Raynaud's phenomenon (Correct answer)
- Acrocyanosis
- Livedo reticularis
Correct answer: Raynaud's phenomenon
Raynaud's phenomenon is characterized by the classic triphasic color change (white→blue→red) in digits triggered by cold or stress.
Question 2: A 3-year-old boy has recurrent Staphylococcus and Aspergillus infections. Neutrophil oxidative burst is absent on dihydrorhodamine test. What is the defective enzyme?
- Myeloperoxidase
- NADPH oxidase (Correct answer)
- Superoxide dismutase
- Adenosine deaminase
Correct answer: NADPH oxidase
Chronic granulomatous disease results from NADPH oxidase deficiency, preventing the respiratory burst needed to kill catalase-positive organisms.
Question 3: A 58-year-old man presents with progressive dysphagia first to solids then to liquids, 15 lb weight loss, and a new hoarse voice. Barium swallow shows a mid-esophageal irregularity. What is the most likely histology?
- Adenocarcinoma
- Squamous cell carcinoma (Correct answer)
- Leiomyoma
- Lymphoma
Correct answer: Squamous cell carcinoma
Mid-esophageal carcinoma is most commonly squamous cell carcinoma, associated with tobacco and alcohol use, unlike distal esophageal adenocarcinoma.
Question 4: A 66-year-old woman has bone pain, serum protein electrophoresis showing an M-spike, and Bence Jones proteins in urine. Skeletal survey reveals lytic lesions. What finding on bone marrow biopsy would confirm the diagnosis?
- >10% plasma cells (Correct answer)
- Reed-Sternberg cells
- Paget cells
- Gaucher cells
Correct answer: >10% plasma cells
Multiple myeloma is confirmed by >10% clonal plasma cells on bone marrow biopsy in the appropriate clinical context.
Question 5: A patient develops sudden-onset severe headache described as 'the worst headache of my life.' CT head is negative. What is the NEXT step?
- MRI brain with gadolinium
- Lumbar puncture for xanthochromia (Correct answer)
- EEG
- Discharge with analgesia
Correct answer: Lumbar puncture for xanthochromia
A negative CT does not exclude subarachnoid hemorrhage; lumbar puncture for xanthochromia is mandatory when clinical suspicion is high.
Question 6: A 52-year-old man undergoes emergent surgery and receives 8 units of packed RBCs. He develops oozing from IV sites and his PT, PTT, and fibrinogen are all abnormal. What is the most likely diagnosis?
- Heparin overdose
- Thrombotic thrombocytopenic purpura
- Disseminated intravascular coagulation (Correct answer)
- Hemolytic transfusion reaction
Correct answer: Disseminated intravascular coagulation
Massive transfusion with dilution coagulopathy combined with trauma triggers DIC, characterized by consumption of clotting factors and fibrinogen.
Question 7: A 14-year-old girl has primary amenorrhea. Exam shows breast development but no pubic hair, and a blind vaginal pouch. Karyotype is 46,XY. What is the diagnosis?
- Turner syndrome
- Congenital adrenal hyperplasia
- Complete androgen insensitivity syndrome (Correct answer)
- Müllerian agenesis
Correct answer: Complete androgen insensitivity syndrome
Complete androgen insensitivity syndrome (46,XY) presents with female phenotype, breast development, absent pubic/axillary hair, and a blind vaginal pouch due to androgen receptor defect.
ECFMG Medical Knowledge & Clinical Science 5
A 25-year-old woman presents with episodic pallor followed by cyanosis then rubor of her fingers triggered by cold.
Which condition is this MOST characteristic of?