[Hairy cell leukemia of European-American type with dual T and B-cell phenotype]

A 46-year-old woman was admitted because of palpitation and conjunctival jaundice. Physical examination revealed hepatosplenomegaly and purpura without lymphadenopathy. Blood count showed 4.7 g/dl hemoglobin with increased reticulocytosis. The platelet count was 1.5 X 10(4)/microliters and the leukocyte count was 6,000/microliters with 17% abnormal mononuclear cells (hairy cells). Hairy cells had nuclei of frequently folded shape and abundant cytoplasma with irregular edges on blood films. The hair-like cytoplasmic projections of the cells were clearly seen under the phase-contrast microscopy. Hairy cells were strongly positive for tartrate resistant acid phosphatase. Bone marrow aspiration was unsuccessful. The biopsy specimens showed small patchy and scattering infiltrations by hairy cells. Surface marker studies of hairy cells revealed that they were strongly positive for SmIg (IgG kappa). They also reacted with alpha B 1, alpha Tac, alpha Leu-M 5 monoclonal antibodies and a rabbit anti-hairy cell serum (alpha HC-M). 53% of hairy cells were shown to react with alpha B 1 and alpha OKT 11 simultaneously by double labelling. The southern blot analysis of peripheral blood mononuclear cells showed IgH chain genes rearrangement and germ line patterns of T-cell receptor genes. Hemolysis was promptly disappeared after blood transfusion. Moreover, the red blood cells, platelets and leukocytes have spontaneously returned to normal levels with disappearance of circulating hairy cells and palpable spleen one year after admission.