Hairy cell leukemia
Hairy cell leukemia is a rare, indolent mature B-cell neoplasm of older men that produces pancytopenia, massive splenomegaly without lymphadenopathy, and recurrent infection, with circulating hairy cells and a dry marrow tap on aspiration. Diagnosis is confirmed by flow cytometry and treatment with a single course of a purine nucleoside analog, typically cladribine, produces durable remission in most patients.
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What this article covers
- Overview
Definition: hairy cell leukemia is a rare, indolent mature B-cell leukemia in which clonal B lymphocytes with fine, hair-like cytoplasmic projections infiltrate the bone marrow, spleen, and blood, producing progressive cytopenias.
- Epidemiology
Rare disease: hairy cell leukemia accounts for a small minority of adult leukemias and is far less common than chronic lymphocytic leukemia.
- Risk factors
Male sex and middle to older age: the demographic in which hairy cell leukemia overwhelmingly occurs.
- Pathophysiology
Clonal mature B-cell proliferation: a single transformed mature B lymphocyte clone acquires characteristic surface markers and cytoplasmic projections, then infiltrates marrow, spleen, and blood.
- Clinical features
Pancytopenia: anemia, thrombocytopenia, and leukopenia are typical; monocytopenia is disproportionately characteristic and helps distinguish hairy cell leukemia from other causes of pancytopenia.
- Differential diagnosis
Myelofibrosis: presents similarly with pancytopenia and massive splenomegaly, but the peripheral smear shows teardrop-shaped cells rather than hairy cells, TRAP staining is negative, marrow fibrosis…
- Diagnosis
Diagnosis is confirmed by flow cytometric immunophenotyping of blood or marrow, positive for the characteristic surface marker panel CD11c, CD25, CD103, and CD123, together with identification of…
- Management
Assess whether treatment is needed before starting therapy: as with other low-grade B-cell disorders, asymptomatic patients with mild cytopenias and no significant splenomegaly or infection can be observed without immediate treatment.
- Complications
Recurrent and opportunistic infection: the most clinically significant complication, driven by neutropenia, monocytopenia, and intrinsic immune impairment; atypical mycobacterial infection is a classic association.
- Prognosis
Excellent with treatment: most patients achieve durable complete remission after a single course of a purine nucleoside analog and have a near-normal life span.
- Prevention
No primary prevention exists: no modifiable risk factor or screening strategy for hairy cell leukemia is established, since the disease has no identified preventable cause.
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