Plasma cell hyperplasia and monoclonal paraproteinemia in human immunodeficiency virus-infected patients

Twenty-seven bone marrow aspirates and biopsy specimens from human immunodeficiency virus-positive patients with plasmacytosis were analyzed to identify the pathologic correlates of polyclonal and monoclonal hypergammaglobulinemia in these patients, to compare the results with another random group of similar human immunodeficiency virus patients with plasmacytosis who did not have serum protein electrophoresis, and to evaluate the significance of the presence of monoclonal proteins in a few patients. Serum protein electrophoresis and immunoelectrophoresis and/or immunofixation electrophoresis revealed monoclonal spikes in five of 18 patients tested. The remaining patients with an abnormal serum protein electrophoresis showed a polyclonal hypergammaglobulinemia. Immunohistochemical stains for kappa and lambda light chains were performed in the bone marrow specimens to determine the presence and/or absence of light-chain preponderance or monoclonality. The percentage of plasma cells varied from 5% to 30% and atypical plasma cells from 1% to 20%. Plasma cell aggregates were present in every case, but variable in number and generally small. In all these cases, including those with monoclonal spikes, plasma cells expressed lambda and kappa light chains with approximately equal intensity. There were no identifiable morphologic differences between the two groups of patients. The paraproteins observed in these patients are likely a reflection of B-cell overactivation. It is important to be aware of this peculiar subset of human immunodeficiency virus-infected patients to avoid an erroneous diagnosis of plasma cell dyscrasia.