Multiple malignant astrocytomas in a patient with spontaneous progressive multifocal leukoencephalopathy.

A 67-year-old man with a four-year history of horizontal and vertical nystagmus and progressive cerebellar dysfunction later developed profound dementia and died of bronchopneumonia. Neuropathological examination revealed numerous active and inactive progressive multifocal leukoencephalopathy (PML) lesions in the cerebrum and cerebellum. Active lesions showed marked perivascular lymphocytic cuffing. Papovaviruses were identified ultrastructurally in both oligodendrocytes and astrocytes. Multiple malignant astrocytomas were documented, originating from PML lesions. No viruses could be demonstrated in neoplastic astrocytes. An immune-deficient state was not revealed clinically or at postmortem examination.