Neuromuscular Disorders USMLE Step 1 Practice Question
A 46-year-old woman presents with 3 months of progressive proximal muscle weakness affecting stair climbing and hair combing. Vital signs: BP 128/82, HR 92, RR 16, Temp 37°C, SpO2 98%. Physical examination reveals no skin rash. Serum creatine kinase is markedly elevated at 3,200 U/L. Electromyography shows myopathic pattern. Muscle biopsy is most likely to show which of the following findings?
Answer choices
- ANeurogenic grouped atrophy from denervation
- BDystrophin deficiency in muscle fibers
- CAmyloid deposition in endoneurial tissue
- DEndomysial inflammation with CD8 positive T cellsCorrect answer
- EPerimysial inflammation with perifascicular atrophy
- FPerivascular eosinophilic infiltrates (eosinophilic myositis)
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