Unusual bone marrow manifestations of parvovirus B19 infection in immunocompromised patients

Parvovirus B19 is responsible for a spectrum of disease in humans. The usua l bone marrow findings in acute parvovirus infections are marked erythroid hypoplasia and occasional giant erythroblasts. Intranuclear inclusions in d eveloping erythroid precursors are rarely described in children or adults w ith parvovirus infection, although abundant intranuclear inclusions are com monly observed in the placenta and other tissues in infected fetuses. In th is study, 8 patients are reported in whom the first evidence of parvovirus infection was the recognition of numerous intranuclear inclusions in erythr oid precursors on bone marrow biopsy sections. Six of the 8 patients had do cumented immunodeficiencies; 4 had acquired immune deficiency syndrome (AID S), and 2 were on chemotherapy. Five of 7 patients were negative for immuno globulin G (IgG) anti-parvovirus antibodies, including all 4 with AIDS. Unl ike the typical pattern in parvovirus infection, the bone marrow was hyperc ellular in most of the patients, and erythroid precursors were usually incr eased with the entire spectrum of normoblast maturation represented; abunda nt intranuclear inclusions were observed similar to the finding in fetuses. The inclusions were variably eosinophilic and compressed the chromatin aga inst the nuclear membrane. In situ hybridization showed parvovirus B19 DNA in numerous erythroid precursors in all cases. The findings of erythroid ma turation and abundant viral inclusions in these immunocompromised patients is consistent with the hypothesis that failure to produce effective IgG par vovirus neutralizing antibodies may lead to persistent infection through vi ral tolerance that allows erythroid development of infected cells past the pronormoblast stage. Identification of parvovirus inclusions in marrow biop sies and subsequent confirmation of infection by in situ hybridization can be important in the assessment of anemia in immunodeficient patients becaus e serological studies for parvovirus B19 are frequently negative. Copyright (C) 2000 by W.B. Saunders Company.