Demyelinating Diseases USMLE Step 1 Practice Question
A 26-year-old female with known multiple sclerosis on interferon-beta therapy presents with progressive cognitive decline, visual disturbances, and ataxia over 4 weeks. Vital signs: BP 118/76, HR 82, RR 16, Temp 37.2°C, SpO2 98%. Brain MRI reveals new multifocal white matter lesions without contrast enhancement. CSF analysis shows JC virus PCR positive; oligoclonal bands negative. Which of the following is the most likely diagnosis?
Answer choices
- ASubacute combined degeneration
- BInterferon-beta-induced demyelination
- CProgressive multifocal leukoencephalopathyCorrect answer
- DMethotrexate-induced leukoencephalopathy
- EMS disease progression
- FNatalizumab-associated IRIS with opportunistic infection
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