what is hairy cell leukemia?
Hairy Cell Leukemia Treatment (PDQÂ®): Treatment - Patient Information [NCI] - General Information About Hairy Cell Leukemia. 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. Anatomy of the bone. The bone is made up of compact bone, spongy bone, and bone marrow. Compact bone makes up the outer layer of the bone.