Abstract
A case of hairy cell leukemia (HCL) with atypical features such as no splenomegaly, no pancytopenia, and L-tartarate sensitive acid phosphatase activity of the hairy cell (HC) is presented. The HC had a morphology of a medium sized lymphoid cell with a wide and irregular lace-like surfaced cytoplasm, and phase contrast microscopically had elongated hairy projections and bizzare pseudopods. The surface marker analysis showed that the HC had receptors for the Fc of IgG and IgM, and for the mouse complement, and had multiple heavy chains (γ, μ, and δ) and a monoclonal light chain (κ) on its surface. And by the analysis with monoclonal antibodies such as anti Leu 1, anti Leu 4, anti Leu 2a, anti Leu 3a, anti Leu 12, anti Leu M1, anti HLA-DR, anti B1, anti B2, and anti J5, the HC had a typical B cell phenotype (positive for Leu 12, B1, B2, and HLA-DR), but after 3 or 4 days culture the HC expressed Leu 1 and Leu M1. About the effects of 12-o-tetradecanoyl phorbol-13-acetate (TPA) on HC, only the morphological changes as found in chronic lymphocytic leukemia (CLL) were reported. The marked expression of Leu 1 and the morphological changes as reported in CLL were found in HC of this case treated with TPA. These results may show the close relationship of HCL and CLL (including CLL related Leu 1 positive B cell malignancy).
