PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY IN AIDS - A CLINICOPATHOLOGICAL STUDY AND REVIEW OF THE LITERATURE

We reviewed the clinical, radiographic, and pathologic features of 15 patients with the acquired immune deficiency syndrome (AIDS) and progr essive multifocal leukoencephalopathy (PML). Brain tissue from 10 auto psy and 6 biopsy specimens was studied using: in situ hybridization (I SH) for JC virus (JCV), immunohistochemistry for human immunodeficienc y virus (HIV) p24 antigen, and electron microscopy. Thirteen patients presented with focal neurologic deficits, while 2 presented with a rap id decline in mental status. PML was commonly the initial opportunisti c infection of AIDS and produced hemiparesis, dementia, dysarthria, ce rebellar abnormalities, and seizures. Magnetic resonance imaging was m ore sensitive than computed tomography in detecting lesions, and often showed multifocal areas of PML. CD4+ T-cell counts were uniformly low (mean 84/mm3), except in 1 patient who improved on 3'-azido-3'-deoxyt hymidine (AZT). PML involved the cerebral hemispheres, brain stem, cer ebellum, and cervical spinal cord. The distribution of brain involveme nt was consistent with hematogenous dissemination of the virus. In 2 b rain specimens, multiple HIV-type giant cells were present within the regions involved by PML. When co-infection by HIV and papovavirus was present, PML dominated the pathological picture. ISH for JCV showed vi rus in the nuclei of oligodendrocytes and astrocytes. Occasionally the re was staining for JCV in the cytoplasm of glial cells and in the neu ropil, the latter possibly a correlate of papovavirus spread between m yelin sheaths, as seen by electron microscopy. ISH demonstrated more e xtensive foci of PML than did routine light microscopy.