Bone Marrow Findings in HIV-positive Patients with Kaposi Sarcoma Herpesvirus-associated Multicentric Castleman Disease

Kaposi sarcoma herpesvirus (KSHV), also known as human herpesvirus-8, is associated with 1 form of multicentric Castleman disease (MCD) and is the etiologic agent for most MCD in human immunodeficiency virus (HIV)-infected patients. Diagnosis is usually determined by lymph node biopsy. Bone marrow findings in KSHV-MCD are not well characterized. We conducted histomorphologic and immunohistochemical evaluation of bone marrow biopsy specimens in HIV-infected patients with KSHV-MCD, including evaluation for KSHV latency-associated nuclear antigen. Findings were correlated with clinical features and KSHV viral load. Reactive plasmacytosis was the predominant feature. Lymphoid aggregates were less common and not diagnostic of KSHV-MCD. Forty-eight percent of cases contained scattered KSHV-infected mononuclear cells. Although patients were generally cytopenic, bone marrow biopsy specimens were normocellular to hypercellular except in patients receiving hematotoxic therapy. Bone marrow biopsy specimens in KSHV-MCD patients recapitulate findings of interleukin-6 excess. In patients with HIV, unexplained cytopenias, and bone marrow plasmacytosis, evaluation for KSHV-MCD is warranted.