NCI Definition: A neoplasm of small B-lymphocytes with "hairy" projections in bone marrow, spleen, and peripheral blood. Most patients present with splenomegaly and pancytopenia. (WHO, 2001) [1]

Hairy cell leukemias most frequently harbor alterations in BRAF [2].

Most Commonly Altered Genes in Hairy Cell Leukemia

BRAF V600E, BRAF Mutation, BRAF Exon 15 Mutation, and BRAF Codon 600 Missense are the most common alterations in hairy cell leukemia [2].

Top Alterations in Hairy Cell Leukemia

Biomarker-Directed Therapies

Significant Genes in Hairy Cell Leukemia



Disease Details

Hairy Cell Leukemia (HCL), Leukemic Reticuloendotheliosis, HCL
Mature B-Cell Neoplasm
Refractory Hairy Cell Leukemia and Splenic Manifestation of Hairy Cell Leukemia
OncoTree Name
Hairy Cell Leukemia
OncoTree Code


1. National Cancer Institute. NCI Thesaurus Version 18.11d. https://ncit.nci.nih.gov/ncitbrowser/ [2018-08-28]. [2018-09-21].

2. The AACR Project GENIE Consortium. AACR Project GENIE: powering precision medicine through an international consortium. Cancer Discovery. 2017;7(8):818-831. Dataset Version 6. This dataset does not represent the totality of the genetic landscape; see paper for more information.

3. All assertions and clinical trial landscape data are curated from primary sources. You can read more about the curation process here.