Perivascular lymphocytes & microglial nodules are seen in -

HIV encephalitis is best characterized microscopically as a chronic inflammatory reaction with widely distributed infiltratesof microglial nodules, sometimes with associated foci of tissue necrosis and reactive gliosis. The microglial nodules also are found in the vicinity of small blood vessels, which show abnormally prominent endothelial cells and perivascular foamy or pigment-laden macrophages. These changes occur especially in the subcoical white matter, diencephalon, and brain stem. An impoant component of the microglial nodule is the macrophage-derived multinucleate giant cell. In some cases, there is also a disorder of white matter characterized by multifocal or diffuse areas of myelin pallor with associated axonal swellingsand gliosis. HIV is present in CD4+ mononuclear. Ref: Robbins Basic Pathology 9th edition pg no 828