ABIM MCQ 3 — Questions and Answers
Question 1: A 38-year-old woman presents with episodic hypertension, diaphoresis, and palpitations. 24-hour urine metanephrines are 4x the upper limit of normal. CT abdomen shows a 3.5 cm right adrenal mass. Before surgical resection, which medication must be initiated first?
- Alpha-blocker (phenoxybenzamine) (Correct answer)
- Beta-blocker (propranolol)
- Calcium channel blocker (amlodipine)
- ACE inhibitor (lisinopril)
Correct answer: Alpha-blocker (phenoxybenzamine)
Alpha-blockade must be established before beta-blockade in pheochromocytoma to prevent unopposed alpha-mediated hypertensive crisis from beta-blockade alone.
Question 2: A 55-year-old man with a 30 pack-year smoking history presents with a 3 cm right upper lobe lung nodule discovered on CT. PET scan shows avid FDG uptake. Mediastinal lymph nodes appear normal. What is the most appropriate next step?
- CT-guided biopsy of the lung lesion (Correct answer)
- Surgical resection without biopsy
- Bronchoscopy with BAL
- Repeat CT in 3 months
Correct answer: CT-guided biopsy of the lung lesion
CT-guided biopsy provides tissue diagnosis before treatment planning for a suspicious solitary lung nodule in a high-risk patient, especially when mediastinal staging is needed.
Question 3: A 62-year-old woman with rheumatoid arthritis on methotrexate and a TNF inhibitor presents with two weeks of fever, night sweats, and cough. CXR shows right upper lobe infiltrate. QuantiFERON-Gold is positive. What is the most appropriate next step?
- Sputum for AFB smear and culture (Correct answer)
- Start empiric isoniazid and pyrazinamide
- Bronchoscopy with BAL
- Hold TNF inhibitor and start full TB treatment empirically
Correct answer: Sputum for AFB smear and culture
Active TB must be ruled out with sputum AFB smear and culture before initiating treatment, as the distinction between latent and active TB changes the regimen.
Question 4: A 48-year-old man presents with progressive fatigue and is found to have iron-deficiency anemia (Hgb 9.2 g/dL). Colonoscopy is negative. Upper endoscopy shows no lesion. Celiac serology is negative. Small bowel capsule endoscopy shows bleeding from the jejunum. What is the most likely diagnosis?
- Gastrointestinal angiodysplasia (Correct answer)
- Meckel's diverticulum
- Crohn's disease
- Small bowel lymphoma
Correct answer: Gastrointestinal angiodysplasia
Angiodysplasia is the most common cause of small bowel bleeding in middle-aged to older adults when upper and lower endoscopy are negative.
Question 5: A 70-year-old woman presents with sudden-onset severe headache rated 10/10, described as 'the worst headache of my life.' CT head is negative. What is the next most critical diagnostic step?
- Lumbar puncture for xanthochromia (Correct answer)
- MRI brain with contrast
- CT angiography of the head
- Observation and analgesics
Correct answer: Lumbar puncture for xanthochromia
A negative CT does not rule out subarachnoid hemorrhage; lumbar puncture demonstrating xanthochromia confirms the diagnosis when CT is non-diagnostic.
Question 6: A 52-year-old man with cirrhosis due to NASH presents with increasing ascites despite diuretic therapy. Paracentesis reveals 680 PMN cells/mm³ in ascitic fluid. He has no abdominal pain. What is the diagnosis and treatment?
- Spontaneous bacterial peritonitis — start cefotaxime IV (Correct answer)
- Secondary peritonitis — emergent surgery
- Malignant ascites — cytology and palliative care
- Chylous ascites — low-fat diet
Correct answer: Spontaneous bacterial peritonitis — start cefotaxime IV
SBP is diagnosed with ascitic PMN ≥250 cells/mm³ and treated with IV cefotaxime; albumin infusion reduces hepatorenal syndrome risk.
Question 7: A 34-year-old woman presents with recurrent DVTs and a miscarriage at 16 weeks gestation. Laboratory workup reveals prolonged aPTT that does not correct with mixing study, positive lupus anticoagulant, and anti-cardiolipin IgG elevated on two occasions 12 weeks apart. What is the most likely diagnosis?
- Antiphospholipid syndrome (Correct answer)
- Factor V Leiden deficiency
- Protein C deficiency
- Systemic lupus erythematosus
Correct answer: Antiphospholipid syndrome
Antiphospholipid syndrome is diagnosed with clinical criteria (thrombosis or pregnancy morbidity) and positive antiphospholipid antibodies on two occasions at least 12 weeks apart.
