Hairy cell leukemia (HCL) is a rare type of blood and bone marrow cancer that affects your B lymphocytes, which are white blood cells that make antibodies to fight infections. If you have HCL Author: Rose Kivi. Hairy cell leukemia (HCL) is a cancer of the blood that starts in your bone marrow -- the soft tissue inside bones where blood cells are made. It happens when your bone marrow makes too many white Author: Angela Nelson.
Hairy cell leukemia is a type of cancer in which the bone marrow makes too many lymphocytes (a type of white blood cell). Hairy cell leukemia is a cancer of the blood and bone marrow.This rare type of leukemia gets worse slowly or does not get worse at all. The disease is called hairy cell leukemia because the leukemia cells look "hairy" when viewed under a microscope.