Clinicopathological study of early progressive multifocal leukoencephalopathy incidentally found in a schizophrenia patient.

A 58-year-old Japanese man developed psychomotor excitement and hallucinatory paranoia at age 53, which gradually developed to residual schizophrenia. He was administered various common tranquilizers until death. Myelodysplastic syndrome was noted 10 months before death. A routine autopsy was performed. The brain weighed 1365 g, and macroscopic observation revealed no remarkable findings. However, microscopic examination disclosed cells with enlarged and basophilic nuclei, and unusual astrocytes in the demyelinated foci, especially at the corticomedullary junctions in the temporal and occipital lobes. On the other hand, the white matter was relatively intact. Immunohistochemical analysis using anti-JC virus protein, VP-1 antibody, demonstrated JC virus-infected cells in not only abnormal glial cells and neurons but also normal-looking cells, which are suggestive of progressive multifocal leukoencephalopathy (PML). Immunostaining for GFAP revealed severe gliosis and some scattered abnormal enlarged nuclear cells in the lesions. Some clusters of CD8-positive lymphocytes were seen, which kill infected cells. PML could be considered a short-term disease preceding death, as "incidental PML" in this case. This is a rare autopsy case of early PML occurring in a schizophrenia patient with PML.