Hairy cell leukemia, an uncommon B-cell lymphoid neoplasia

Hairy cell leukemia (HCL) is an uncommon B-cell lymphoid neoplasia, representing 2–3% of all leukemias. It is more common in men, with a median age at diagnosis of 52 years. The hair-like projections on its surface are its principal characteristic. Although its etiology has not been established, the recent gene sequencing of HCL identified the presence of the BRAF V600E mutation, absent in other malignant neoplasias of the lymph cells. The clinical course of the disease is usually indolent. The majority of patients initially present weakness and fatigue, pancytopenia and splenomegaly.

HCL must be distinguished from other indolent lymphoid neoplasias such as prolymphocytic leukemia, splenic marginal zone lymphoma, the variant of HCL (HCLv), and mantle cell lymphoma. Peripheral blood flow cytometer is essential for the detection of CD11c, CD19, CD20, CD22, CD25, and CD10, as well as a bone marrow aspirate to detect immunophenotypes. In addition, a bone biopsy is useful to perform an immunohistochemistry analysis for TRAP, DBA-44 and A1 annexin.

Purine analogues remain the first line of treatment. However, interferon and rituximab are a valid option, if the ideal treatment is unavailable. New discoveries in the pathophysiology of HCL have brought the creation of pharmaceuticals with distinct therapeutic targets. These pharmaceuticals are currently undergoing testing.