| nature abnormality of human immunodeficiency virus | | | | parvovirus. |
| (HIV) infection is the decline in the number of CD4 | | | | Although the utility of bone marrow aspirate and |
| lymphocytes over time. However, other cytopenias | | | | biopsy in an HIV-infected patient with low blood |
| also are seen in advanced disease, with anemia | | | | counts has been debated, morphologic changes such |
| reported in 60%, thrombocytopenia in 40%, and | | | | as giant pronormoblasts in parvovirus infection and |
| neutropenia in 50% of patients with acquired | | | | special stains for mycobacteria and fungi may hasten |
| immunodeficiency syndrome (AIDS). These | | | | identification of a reversible cause of |
| cytopenias occur in conjunction with progressive | | | | myelosuppression. Marrow sampling is not more |
| deterioration of immune function and are less | | | | sensitive, however, than routine microbiologic tests in |
| common in the earlier stages of HIV infection or in | | | | diagnosing these abnormalities. |
| patients responding to antiretroviral medications. | | | | Morphologic abnormalities of myeloid and erythroid |
| Thrombocytopenia is the exception and may | | | | lineages often are present in the bone marrow of |
| constitute a manifestation of HIV infection during the | | | | patients with HIV disease in the absence of infection |
| asymptomatic phases. | | | | or neoplasm. These changes are nonspecific and |
| Multiple contributing factors frequently are operative | | | | include hypercellularity, dysplasia with frequent |
| in the cytopenia in advanced HIV infection, including | | | | megaloblastosis, lymphoid aggregates, and increased |
| direct and indirect effects of HIV; opportunistic | | | | plasma cells and reticulin. The pathogenetic |
| infections; neoplasms; and toxic antiretroviral, | | | | mechanisms for these morphologic abnormalities and |
| antimicrobial, or antitumor chemotherapy. Evaluation | | | | the associated impaired hematopoiesis are not well |
| of patients with low blood counts should focus on | | | | defined. Laboratory studies of hematopoiesis in HIV |
| infectious processes and attendant myelotoxic | | | | infection have yielded variable and differing results. |
| effects of therapy. | | | | The bulk of evidence suggests that HIV does not |
| In addition to the usual laboratory approaches to | | | | directly infect early progenitors but may alter the |
| cytopenia based on impaired production, excess | | | | proliferative capacity of progenitors by two possible |
| consumption, and/or sequestration, a number of | | | | mechanisms: (1) induction of inhibitory factors in the |
| other diagnostic studies should be considered. These | | | | marrow microenvironment, or (2) interaction with the |
| include blood isolator cultures for fungi and | | | | progenitor cell surface and induction of cell death |
| mycobacteria, and serum assessment for | | | | (apoptosis) without infecting stem cells. |
| cytomegalovirus (CMV) antigen or IgM antibody to | | | | |