Unusual presentation of relapsed hairy cell leukemia. The patient is a 64-year-old man with hairy cell leukemia diagnosed in 1982 and had been in partial remission after treatment with splenectomy (1982), intermittent courses of α-interferon (1987-1994), and pentostatin (1994). In May 1996, he developed bilateral bony masses in the tibia, each about 6 cm in diameter (A), and a lump in the mucosa of the lower lip. He also had generalized lymphadenopathy, hepatomegaly of 5 cm, a hemoglobin level of 9.8 g/dL, a platelet count of 91 × 109/L, and a leukocyte count of 12 × 109/L with 70% hairy cells. Marrow trephine biopsy showed substantial replacement of normal hematopoietic tissue by hairy cells (B) and reticulin fibrosis. The buccal mucosal mass proved, on biopsy, to be a deposit of leukemic cells. Five weeks after a 7-day course of 2-chlorodeoxyadenosine, the tibial masses had resorbed (C). Repeat marrow biopsy 3 weeks later showed few hairy cells and a normal amount of reticulin. At follow-up 11 weeks after chemotherapy, the hematologic parameters were a hemoglobin level of 12.8 g/dL, a platelet count of 199 × 109/L, a white blood cell count of 6.5 × 109/L, a granulocyte count of 3.1 × 109/L, and a lymphocyte count of 2.9 × 109/L. There were no hairy cells in the peripheral blood film. (Courtesy of I.E. Okpala, MRCPath, FWACP, Central Sheffield University Hospitals, Royal Hallamshire Hospital, Glossop Road, Sheffield, UK, and J. Leslie, FRCPath, Norfolk & Norwich Hospital, Norwich, UK.) {/ANNT;;;left;0n}
