Hairy Cell Leukemia

Definition

Hairy cell leukemia (HCL) is a rare, slow-growing type of blood cancer that starts in B lymphocytes, a type of white blood cell. The cells appear “hairy” under a microscope due to tiny projections from their surface.

Characteristics

HCL often leads to low blood cell counts, causing fatigue, frequent infections, and easy bruising or bleeding. Enlargement of the spleen (splenomegaly) is common, leading to abdominal discomfort or fullness.

Diagnosis and Prognosis

Diagnosis involves blood tests, bone marrow biopsy, and flow cytometry to identify characteristic hairy cells. Prognosis is generally excellent, with most patients responding well to treatment and living many years after diagnosis.

Treatment

Treatment typically includes chemotherapy with purine analogs, such as cladribine or pentostatin. In some cases, targeted therapies or immunotherapy may be used. Many patients experience long-term remissions after initial treatment.

Last Revised: 12 May , 2025