Human immunodeficiency virus and papovavirus infections in acquired immunodeficiency syndrome: an ultrastructural study of three cases.

A wide variety of neurologic conditions associated with the acquired immunodeficiency syndrome (AIDS) have been attributed to human immunodeficiency virus (HIV) infection of the central nervous system (CNS). Tissue samples from the brains of three patients with AIDS, diagnosed as having CNS toxoplasmosis on the basis of computed tomographic scans of the head, were studied by transmission electron microscopy. In two, HIV particles were observed budding from, in close association with, and in cytoplasmic vacuoles of mononuclear and multinucleated macrophages, but no other cell types. The patient with the greatest number of HIV particles also had large amounts of papovavirus (progressive multifocal leukoencephalopathy) in the nuclei of oligodendroglial cells and in the cytoplasm of astrocytes. These astrocytes often had atypical features at the light microscopic level. Following an initial biopsy that showed only HIV, primary CNS lymphoma was diagnosed by needle biopsy and confirmed at autopsy in a second case. A diagnosis of progressive multifocal leukoencephalopathy was rendered by transmission electron microscopy in a third case, but no HIV was detected. Toxoplasmosis was not confirmed in any of the three cases. Diagnosis of CNS lesions in patients with AIDS should not rely exclusively on radiography but include biopsy for both light and transmission electron microscopy. Transmission electron microscopy can be employed to reveal HIV and papovavirus infections not discernible at the light microscopic level and should be used as a diagnostic tool in HIV-related infections.