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, ATM, NF1, EP400, and DNMT3A [2].

Most Commonly Altered Genes in Hairy Cell Leukemia

BRAF V600E, BRAF Mutation, BRAF Exon 15 Mutation, BRAF Codon 600 Missense, and ATM Mutation 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

HCL, Leukemic Reticuloendotheliosis, Hairy Cell Leukemia (HCL)
Mature B-Cell Neoplasm
Splenic Manifestation of Hairy Cell Leukemia and Refractory 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 8. 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.