PML or PMLE. Viral disease in immunosuppressed. Demyelination -> Multifocal.
Etiology
JC Polyoma Virus.
Pathology
Infects Oligodendrocytes –> causes demyelination.
Clinical features
Asymptomatic in childhood. But serology positive.
Reactivates during immunosuppression.
Focal progressive neurological symptoms.
Imaging: Multifocal white matter lesions.
Morphology
Gross: Variably sized small to large irregular ill-defined white matter lesions in subcortical areas of cerebrum and cerebellum.
Microscopy: Central lipid laden macrophages, with paucity of axons. Surrounded by oligodendrocytes with viral nuclear inclusions -> Glassy amphophilic body within enlarged nucleus.
Bizarre giant astrocytes + (Reactive).