Neuropathological studies in the brains of AIDS patients with opportunistic diseases.

The brains of 70 fatal cases with AIDS were studied by means of immunohistochemistry and in-situ hybridization in a consecutive autopsy series (1985-July 1992). In addition, the neuropathological changes were correlated with the neurological and neuroimaging findings. Opportunistic infections included toxoplasmosis (15 cases), cytomegalovirus (CMV)-encephalitis (6), progressive multifocal leucoencephalopathy (2) and fungal infections (3). Malignant lymphomas were found in 7 patients; 6 involved primarily the CNS, one was metastatic. In 14 cases the neuropathological changes were consistent with HIV encephalitis and HIV leucoencephalopathy. Non-specific lesions occurred in 31 cases. The clinical diagnosis in patients with opportunistic diseases (n = 27) diverged in 15 cases (55%) from the underlying pathology. Toxoplasma gondii, CMV and JC viruses were identified by immunohistochemistry and in-situ hybridization on serial paraffin sections. In addition, antibodies against lymphocyte subsets, tissue macrophages, the glial fibrillary acid protein (GFAP) and myelin basic protein were used to characterize the phenotype of cells and to highlight the degree of gliosis and demyelination. Our results show that the distribution and degree of morphological changes might be helpful for the differential diagnosis antemortem. Since neurological complications may represent the first or sole manifestation of AIDS and risk factors for AIDS are often not known, it should be taken into account that CNS manifestations of AIDS may contribute to a sudden and unexpected death or accident. Opportunistic diseases should be considered as a possible differential diagnosis in cases mimicking the clinical picture of apoplexia or dementia. Furthermore, CNS lesions may be detected postmortem in patients who were not known to suffer from Neuro-Aids during life, indicating that CNS involvement is more widespread than assumed.