Human immunodeficiency virus (HIV, AIDS)

General:

Clinical:

• Normal:
• Abnormal:

Resistance:

Morphology:

• Lymph nodes: 3 histological patterns, A, B, and C, have been described that generally correspond to clinical stages of acute, chronic, and burnout (NEJM 1993; 328: 327; Am J Surg Pathol 1996;20:572), as well as likelihood of progression to AIDS. Pattern A shows greatly enlarged lymphoid follicles comprised of reactive hyperplastic germinal centers with widespread apoptosis, phagocytosis of nuclear debris, and small lymphocytes penetrating/disrupting the germinal centers (folliculolysis); similar to that seen in infectious mononucleosis, cytomegalovirus, varicella, measles, and toxoplasma lymphadenitis. Pattern B is a transition from pattern A to pattern C. It includes effacement of follicles, disruption of dendritic cells, and involution of germinal centers and is suggestive of subacute or chronic lymphadenitis; similar to that seen in Castleman (plasma cell type), and angioimmunoblastic lymphadenopathy. Pattern C shows atrophic, burned-out follicles and extensive, diffuse vascular proliferation. The interfollicular cortex shows loss of lymphocytes but plasma cells and fibrosis are seen; similar to that seen in Castleman (hyaline vascular type) and fibrosed end-stage lymphadenitis.
• Bone marrow: Nonspecific findings, although some degree of marrow suppression, plasmacytosis, and an associated "anemia of chronic disease" is frequently found. Usually hypercellular or normocellular, rarely hypocellular. M:E ratio usually normal, or slight myeloid hyperplasia. Mild maturation abnormalities include ringed sideroblasts and megaloblastic changes. Other abnormalities include polyclonal lymphoid aggregates, plasmacytosis, myelofibrosis, fat necrosis, and granulomata (about half of which are associated with an identified organism).

Growth characteristics:

Common/important pathogens: