VIII. Progressive Multifocal Leukoencephalopathy (PML)
C. Pathological changes
Gross pathology: Multiple and/or widespread areas of demyelination
Microscopic pathology: Inclusion bodies in oligodendroglia nuclei; transformed bizarre astrocytes and gliosis; numerous areas of demyelination (due to oligodendrocyte dysfunction). Lesions are primarily in subcortical white matter, but also occur in brainstem and cerebellum. Ultrastructural changes include identification of papovavirus particles in the oligodendroglial nuclear inclusions.