Hairy Cell Leukemia

Mark B. Geyer, Omar Abdel-Wahab, Martin S. Tallman, Jae H. Park

Research output: Chapter in Book/Report/Conference proceedingChapter


Hairy cell leukemia is a rare, chronic B cell lymphoproliferative disorder, more commonly diagnosed in men than in women, and typically arising in the middle decades of life. An activating mutation in BRAF (V600E) is present in nearly all cases of hairy cell leukemia and represents a disease-defining genetic event. A distinct, very rare B cell lymphoproliferative disorder called hairy cell leukemia variant lacks BRAF mutations. Multilineage cytopenias and splenomegaly are the most common clinical signs present at diagnosis. Fine, hair-like cytoplasmic projections are a distinctive morphologic finding on peripheral blood smear, though diagnosis is typically confirmed by immunophenotype (by flow cytometry) and/or by bone marrow core biopsy; the marrow is frequently inaspirable. Expectant management following diagnosis is appropriate in a subset of patients. Treatment is indicated for progressive cytopenias, symptomatic organomegaly or adenopathy, frequent infections due to neutropenia, or disease-related constitutional symptoms. Purine analogs (cladribine, pentostatin) constitute the initial therapeutic agents of choice in most patients, and most will achieve durable complete response following a single cycle of cladribine. The CD20-targeted monoclonal antibody rituximab has demonstrated activity as well, as a single agent or in combination with cladribine. BRAF inhibitors and CD22-targeted recombinant immunotoxins have demonstrated high rates of response in patients with relapsed or refractory hairy cell leukemia in early-phase clinical studies.

Original languageEnglish (US)
Title of host publicationAbeloff’s Clinical Oncology
ISBN (Electronic)9780323476744
StatePublished - Jan 1 2019


  • BRAF V600E
  • Cladribine
  • Hairy cell leukemia
  • Lymphoproliferative disorders
  • Pancytopenia
  • Rituximab
  • Splenomegaly
  • Vemurafenib

ASJC Scopus subject areas

  • Medicine(all)


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