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PML in Immunosuppressed SLE — RACP Adult Medicine MCQ

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HardNeurologyPML in Immunosuppressed SLERACP Adult Medicine

A 35-year-old woman with SLE on mycophenolate and prednisolone 15 mg daily develops progressive cognitive decline and behavioural changes over 4 weeks. MRI shows non-enhancing white matter lesions. CSF shows no cells but JC virus PCR is positive. CD4 count is 280 cells/μL. She has no lupus activity serologically. What is the most likely neurological complication?

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Correct answer: D — Progressive multifocal leukoencephalopathy

Progressive cognitive/behavioural decline with non-enhancing multifocal white matter lesions and positive CSF JC virus PCR in an immunosuppressed SLE patient is PML. PML results from JC virus reactivation causing oligodendrocyte destruction (demyelination). Unlike NPSLE, PML has no lupus serological activity and positive JC virus. No proven antiviral exists — treatment is immune reconstitution (reduce/stop immunosuppression). Prognosis is poor (mortality ~30-50%).

Reference: eTG Neurology – 2024 – PML; AAN 2019 PML