Autopsy case of the cerebellar form of progressive multifocal leukoencephalopathy without immunodeficiency

Area of Science:

• Neurology
• Virology
• Pathology

Background:

• Progressive multifocal leukoencephalopathy (PML) is typically associated with severe immune deficiency.
• This case presents a rare cerebellar form of PML in a patient without overt immunodeficiency.

Observation:

• A 74-year-old woman with chronic renal failure and anemia developed progressive neurological symptoms including fatigue, gait disturbance, and articulation disorder.
• Clinical presentation did not suggest immunodeficiency or PML, and she did not receive immunosuppressive therapy.
• Post-mortem examination revealed diffuse demyelination in the cerebellum, moderate in the brainstem, and mild in the cerebrum.

Findings:

• JC virus antigen was frequently found in demyelinated lesions in the cerebrum and brainstem, but rarely in the cerebellum.
• The degree of demyelination in different brain regions was inversely correlated with the number of JC virus-infected cells.
• These observations suggest variability in demyelination severity relative to viral presence in PML.

Implications:

• PML can manifest with varying degrees of demyelination, not always directly correlating with JC virus detection in all affected areas.
• Consideration of inverse correlation between demyelination and JC virus load is crucial for interpreting brain biopsies in suspected PML cases.
• This case highlights the importance of considering atypical presentations of PML, even in the absence of profound immunosuppression.