Dementia with Lewy bodies — SCE Neurology MCQ

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HardCognitive NeurologyDementia with Lewy bodiesSCE Neurology

A 71-year-old develops progressive proximal weakness and CK 11,500 IU/L nine months after atorvastatin was stopped. MRI shows diffuse muscle oedema; there is no rash or interstitial lung disease. Which test is most likely to identify the disease-defining autoimmune target?

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Correct answer: D — Serum anti-HMGCR antibody

Explanation lettering: C = shown as B · E = shown as C · B = shown as E

D is correct: persistent or progressive necrotising myopathy despite statin withdrawal is the classic setting for anti-HMGCR immune-mediated necrotising myopathy. Anti-cN1A can support inclusion-body myositis, which is usually slower with finger-flexor and knee-extensor selectivity and a lower CK. Anti-Jo-1 points toward antisynthetase syndrome. Anti-SRP can also cause necrotising myopathy, but the statin-linked phenotype makes HMGCR the most discriminating target; antibody testing and biopsy are complementary rather than sequentially exclusive.

Reference: Muscle biopsy: what and why and when?: https://pn.bmj.com/content/20/5/385