A 44 year-old male presents with a several-week history of progressive weakness and visual changes. His family has noted a personality change over the past few months. An MRI shows multifocal, non-enhancing lesions involving the cortical white matter. A biopsy of one of the lesions is shown here.



What is the most likely cause of this patient’s symptoms?

A. Creutzfeld-Jakob disease
B. Cryptococcal infection
C. Toxoplasmosis
D. Herpes encephalitis
E. Progressive multifocal leukoencephalopathy






(Scroll down for the answer)








The diagnosis in this case is progressive multifocal leukoencephalopathy, or PML, a disease caused by a polyomavirus called the JC virus. At least half of the general population has been exposed to the JC virus – but PML occurs almost exclusively in immunocompromised patients.

PML is a demyelinating disease that predominantly affects the subcortical white matter. Typical symptoms include weakness, paralysis, vision loss, impaired speech, deterioration of cognitive function, and personality change. Diagnosis is made on demonstration of JC virus DNA in cerebrospinal fluid, or on brain biopsy, which shows infected oligodendrocytes and astrocytes with large, round, dark nuclear inclusions, as seen in this image. There is no cure; however, patients with AIDS may survive for years with the use of highly active antiretroviral therapy.

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