Central Nervous System
Perivascular lymphocytes and microglial nodules are seen in: (AIIMS Nov 2012)
• HIV encephalitis is best characterized microscopically as a chronic inflammatory reaction with widely distributed infiltrates of microglial nodules.
• The microglial nodules are also found in the vicinity of small blood vessels, which show abnormally prominent endothelial cells and perivasular foamy or pigment-laden macrophages. These changes occur especially in the subcortical white matter, diencephalon and brainstem.
• An important component of the microglial nodule is the macrophage-derived multinucleated giant cell.