The Treatment of Hairy Cell Leukemia: A Review

Hairy cell leukemia is a chronic lymphoproliferative malignancy first described by Bouroncle et al. over 30 years ago¹. Representing less than 2% of adult leukemias, hairy cell leukemia has become the focus of intense interest over the past few years as a result of therapeutic advances. The malignant cell has characteristic irregular cytoplasmic projections visible on the peripheral blood smear and cytoplasmic vesicles staining positive for tartrate-resistant acid phosphatase. The origin of the hairy cell appears to be a preplasma cell B lymphocyte based on immunoglobulin gene rearrangements and B-cell-specific antigens, although very rare T-cell variants have been reported. While the diagnosis may be suspected from the clinical manifestations and examination of the peripheral smear, a bone-marrow biopsy is frequently necessary for definitive diagnosis. The typical patient is a middle-aged man with complaints of fatigue or weakness; symptoms of splenic pain, bleeding or bruising, or recurrent infections are less common at presentation². Splenomegaly without peripheral adenopathy occurs in 70-80 % of newly diagnosed patients². Pancytopenia is present in approximately two-thirds of patients, although 10% of patients present with a leukocytosis resulting from a high circulating hairy cell count.