Page 208 - AIDSBK23C

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in about half of cases of disseminated MAC. Acid fast staining of marrow biopsies is positive in
about a third of cases, but is the most rapid method of detection.[853]
A hemophagocytic syndrome has been described in association with HIV infection. A
malignancy is the underlying etiology in over half of cases, and an opportunistic infection in over
40% of cases. Fever, splenomegaly, hepatomegaly, lymphadenopathy, peripheral blood
cytopenias, hypertriglyceridemia, hypofibrinogenemia, and hyperferritinaemia are common
findings. Diagnosis is made on bone marrow biopsy.[854]
Toxoplasmosis involving marrow may be subtle. Features can include interstitial edema,
focal necrosis, and only a few scattered macrophages or clusters of macrophages. The
tachyzoites and pseudocysts are found in or around areas of necrosis. Organisms may be found
not only in macrophages but also in granulocytes and megakaryocytes.[855]
Parvovirus B19 infection may not always be detected by finding the presence of
intranuclear pink inclusions within erythropoietic precursors. By the in situ hybridization
technique, parvovirus may be detected in less than 10% of marrows in patients with AIDS.
Infection is typically detectable late in the course of AIDS. Few infected patients have severe
anemia.[842]

NEOPLASMS IN BONE MARROW.-- Non-Hodgkin lymphomas (NHL’s) involve the
bone marrow in about one fourth of cases in which they are diagnosed at autopsy. Bone marrow
biopsy is of value in staging of these lymphomas.[850] The small noncleaved Burkitt or Burkitt-
like lymphomas are more likely to involve marrow than those of a diffuse large cell variety.
Low-grade lymphomas are seen far less frequently and are not part of definitional criteria for
AIDS. Non-Hodgkin lymphomas that involve some other site in persons with AIDS are seen in
the marrow in 25% of cases. Patients with bone marrow involvement with NHL are more likely
to have meningeal involvement. Patients with marrow involvement are more likely to have high
lactate dehydrogenase levels, fever, night sweats, and/or weight loss, and such patients tend to
have shorter survival. Survival is decreased with >50% marrow involvement.[856]
Many AIDS cases occur in patients in the same peak age group range in which myelogenous
leukemias and Hodgkin lymphoma may be seen, but these entities not diagnostic for AIDS.
Low-grade lymphomas must be distinguished from the benign reactive lymphoid aggregates
found in about one third of HIV-infected patients. Such benign aggregates are usually not in a
peritrabecular location, however. A plasmacytosis may be present in AIDS patients or in HIV-
infected patients prior to development of clinical AIDS, but the proliferation is polyclonal, as
demonstrated by immunohistochemical staining with antibody to lambda and kappa
immunoglobulin light chains. Hodgkin lymphoma associated with HIV infection has a
propensity for bone marrow involvement.[561] Kaposi's sarcoma is very rarely seen in bone
marrow, and when it does occur in marrow, is widely disseminated.[857]
Multicentric Castleman disease (MCD) involving bone marrow is characterized by the
appearance of small lymphoid follicles with depleted germinal centers and a surrounding mantle
zone containing plasmablasts containing human herpesvirus-8 (HHV-8) by
immunohistochemistry. Surrounding sinusoids contain increased plasma cells. Patients often
have pancytopenia.[858]