Fine needle aspiration of the spleen in hairy cell leukemia. A case report.

Hairy cell leukemia (HCL), or leukemic reticuloendotheliosis, first described by Bouroncle in 1958, is a chronic lymphoproliferative disorder of B-cell origin that is manifest primarily in the blood, marrow and spleen. The hairy cells often contain a tartrate-resistant acid phosphatase (TRAP) isoenzyme and show prominent cytoplasmic projections. We report a rare case of hairy cell leukemia wherein the total white blood cell count in the peripheral blood was 20 x 10(9)/L, there were hairy cells in the peripheral blood, and the bone marrow aspirate was a dry tap. Fine needle aspiration of the spleen was performed. The splenic smears showed a monotonous population of abnormal lymphoid cells, some with the hairlike cytoplasmic projections. TRAP staining was positive. HCL must be differentiated from splenic B-cell lymphoma with circulating villous lymphocytes.