Neuromuscular Disorders USMLE Step 1 Practice Question
A 72-year-old man presents with slowly progressive proximal weakness over 2 years, affecting stair climbing and grip strength. Vital signs: BP 138/82, HR 88, RR 16, Temp 37.2°C, SpO2 98%. Serum CK is mildly elevated at 650 U/L. Muscle biopsy shows endomysial inflammation with rimmed vacuoles and acid-phosphatase positive inclusions. No dysphagia or cardiac involvement noted. Which of the following is the most likely diagnosis?
Answer choices
- ADermatomyositis
- BInclusion body myositisCorrect answer
- CGuillain-Barré syndrome
- DPolymyositis
- EMyotonic dystrophy
- FLate-onset Pompe disease (acid maltase deficiency)
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