BONE-MARROW GRANULOMAS ASSOCIATED WITH CHRONIC NATURAL-KILLER-CELL LYMPHOCYTOSIS

Two patients with chronic natural killer cell lymphocytosis (CNKL) and associated bone marrow granulomas (BMGs) are described. The increases in the peripheral blood of both the proportion (64 and 74%) and absol ute number (2,000/mu L and 4,700/mu L) of NK cells have persisted for more than 1 and 3 years. One patient was asymptomatic with thrombocyto penia and neutropenia, and the other presented with fever of unidentif ied origin, which has since responded to a nonsteroidal anti-inflammat ory agent. Bone marrow examination in both patients showed loose aggre gates of epithelioid histiocytes similar to the noncaseating granuloma s seen in other diseases. An unusual feature, however, was the presenc e of many scattered, large mononuclear histiocytes that were morpholog ically similar to atypical megakaryocytes. Extensive clinical and labo ratory studies did not reveal an established cause for the BMGs. BMGs may be associated with CNKL, with the unusual feature of scattered, at ypical mononuclear histiocytes. (C) Wiley-Liss, Inc.