ANATOMOPATHOLOGY OF ENCEPHALOMYELITIS CAUSED BY CYTOMEGALOVIRUS AND VARICELLA-ZOSTER VIRUS

Cytomegalovirus (CMV) infection of the nervous system is frequent in acquired immunodeficiency syndrome (AIDS) and can be responsible for encephalitis, encephalomyelitis, meningoradiculitis or polyradiculo-neuropathy. Encephalitis is characterized at microscopy by its periventricular and cerebellar location, and by the presence of cytomegalic cells, containing intranuclear and/or intracytoplasmic inclusions, microglial nodules and necrotic foci, The virus can infect almost all types of cells. Coexistence of CMV and HIV has been observed in giant cells of macrophagic origin. It has been suggested that the two viruses could act in synergy. The nervous system is seldom infected by the varicella-zoster virus (VZV) in AIDS. The infection can be responsible for multifocal leukoencephalitis, ventriculitis, vascular lesions associated or not with cerebral infarction, or with meningomyeloradiculitis. In almost all cell types Cowdry's type A intranuclear inclusions have been found. The virus can be demonstrated by immunohistochemistry or in situ hybridization. VZV antigens have been reported in the walls of vessels damaged by a non inflammatory obliterating vasculopathy or by a granulomatous angiitis. Coexistence of VZV and HIV has been observed in giant cells of macrophagic origin, and synergy between those two viruses has been suspected.