RESUMO
We experienced a case of atypical hairy cell leukemia in a 42-year-old woman. She showed marked splenomegaly without palpable lymphadenopathy. Complete blood cell count revealed leukocytosis at 44,000/micro L with lymphocytes 74% and peripheral blood smear showed abnormal lymphoid cells with cytoplasmic projections. The bone marrow was easily aspirated and also revealed the abnormal lymphocytes in up to 95%. Tartrate-resistant acid phosphatase reactivity was negative in the hairy cells. Immunophenotyping results of lymphoid cells were CD5(-), CD7(-), CD10(-), CD19(+), and HLA-DR(+). She was treated with an adenosine analogue, fludarabine at a daily dose of 30mg/m2 for 5 consecutive days, every four weeks. Immediately after treatment, the size of the spleen was normalized. Correct diagnosis was difficult due to insufficient laboratory and pathologic data. The differential diagnosis of mature B-cell neoplasms with cytoplasmic projections in patients with splenomegaly includes hairy cell leukemia and splenic lymphoma with villous lymphocytes. We herein described the present case with a brief review of the literature.