A 38-year-old man with AIDS (CD4 count 80 cells/μL) presents with progressive right-sided weakness and speech difficulty over 3 weeks. MRI shows multifocal white matter lesions without mass effect. PCR of CSF is positive for JC virus. What is the most likely diagnosis?

• A Cerebral toxoplasmosis
• B Primary CNS lymphoma
• C HIV encephalopathy
• D Progressive multifocal leukoencephalopathy ✓

Explanation

Progressive multifocal leukoencephalopathy (PML) is caused by JC virus reactivation in immunocompromised patients, particularly those with HIV and CD4 counts below 200. It presents with focal neurological deficits and characteristic multifocal white matter lesions on MRI without mass effect. Toxoplasmosis and lymphoma typically show ring-enhancing lesions with mass effect. HIV encephalopathy is more diffuse.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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