What is Hairy Cell Leukemia?

Leukemia is cancer that forms in your bone marrow, the soft, spongy tissue inside your bones where blood cells are produced. Your bone marrow contains immature, blood-forming stem cells that eventually develop into mature red blood cells, white blood cells, and platelets. In hairy cell leukemia, your bone marrow makes too many abnormal B-cell lymphocytes, a type of white blood cell that fights infection. These excess B-cell lymphocytes can crowd out your healthy blood cells causing conditions like anemia (low red blood cells), leukopenia (low white blood cells), and thrombocytopenia (low platelets). The abnormal lymphocytes in hairy cell leukemia have projections on their surface that make them look hairy under a microscope. Hairy cell leukemia progresses very slowly compared to other forms of leukemia; however, the abnormal cells can eventually build up in your body and invade your blood and other organs, such as the spleen.