Progressive multifocal leukoencephalopathy in a patient without apparent immunosuppression

Area of Science:

• Neurology
• Virology
• Pathology

Background:

• Progressive multifocal leukoencephalopathy (PML) is a rare, demyelinating disease affecting the brain's white matter.
• PML is typically associated with severe immune deficiency, often caused by the John Cunningham (JC) virus.

Observation:

• An 80-year-old man presented with dysphagia and left-sided weakness.
• Initial MRI showed white matter abnormalities; CSF PCR for JC virus was negative.
• Brain biopsy revealed foamy macrophages and positive staining for anti-simian virus 40 antibodies.

Findings:

• Postoperative CSF PCR confirmed JC viral DNA, establishing the diagnosis of PML.
• Extensive investigations failed to identify any underlying immunocompromising disorder.
• The patient experienced rapid neurologic deterioration and died 3.5 months post-diagnosis.

Implications:

• This case highlights the possibility of PML in elderly individuals without apparent immune compromise.
• It underscores the diagnostic utility of brain biopsy when initial PCR tests are negative.
• The findings prompt consideration of atypical presentations of PML and the need for thorough etiological investigation.