Rapidly progressive multifocal leukoencephalopathy with substantial cell-mediated inflammatory response and with cognitive decline of non-Alzheimer type in a 75-year-old female patient.

Autopsy findings of rapidly progressive and widespread multifocal leukoencephalopathy (PML) in a 75-year-old woman with no known predisposing disease are demonstrated. Originally she was given a clinical working diagnosis of syndrome of progressive supranuclear palsy (PSP). The neuropathological investigation revealed widespread white and gray matter changes consistent with PML, and the JC virus was verified by EM, in situ hybridization and immunohistochemistry. In contrast to the few chronic inflammatory cells generally seen in PML in this case there was a substantial cell-mediated inflammatory response reflected in numerous T-helper and T-killer cells. The uncommon, widespread distribution of lesions and substantial cell-mediated response reported might indicate that the rearrangement of viral genome, previously suggested of importance for viral growth in the central nervous system (CNS), is also important for viral spread within the CNS, infectivity of glial cells and for the activation of cell-mediated immunity.