TY - CHAP M1 - Book, Section TI - Hairy Cell Leukemia A1 - Grever, Michael R. A1 - Lozanski, Gerard A2 - Kaushansky, Kenneth A2 - Prchal, Josef T. A2 - Burns, Linda J. A2 - Lichtman, Marshall A. A2 - Levi, Marcel A2 - Linch, David C. Y1 - 2021 N1 - T2 - Williams Hematology, 10e AB - SUMMARYHairy cell leukemia (HCL) is an uncommon form of adult chronic B-cell leukemia. Whereas the cell of origin is uncertain, at diagnosis the characteristic leukemic cells are found in the marrow, the blood, and the spleen. Patients present with fatigue and infections, and many have splenomegaly. They are often pancytopenic or may have isolated cytopenias and usually have monocytopenia. The leukemic cell in classic hairy cell leukemia (HCL-c) has a characteristic immunophenotypic profile (CD11c+, CD19+, CD20+bright, CD22+, CD25+, CD103+, and CD123+ and CD27−). A variant of hairy cell leukemia (HCL-v), which occurs less frequently, has been identified as a separate entity. A genetic mutation, BRAF V600E, has been identified in the majority of patients with the classic form of this disease but is not present in the variant. This mutation is also present in the hematopoietic stem cells of patients with HCL-c.HCL is characterized by impaired marrow function and immunity, leading to a high incidence of infectious complications. Both pentostatin and cladribine are effective in achieving durable complete remissions. Long-term studies demonstrate prolonged survival of patients, but the disease-free survival curves do not plateau, suggesting that the disease is not cured but subject to relapse. Survival has been markedly improved with the introduction of purine nucleoside analogues and is estimated to be 90% at five-year follow-up. When patients relapse, high-quality remissions can be achieved with salvage therapy. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - hemonc.mhmedical.com/content.aspx?aid=1180447530 ER -