SEM of abnormal white blood cells from a person suffering from hairy cell leukemia. The cells show characteristic hair-like cytoplasmic projections. A normal red blood cell shows comparative size. Leukemia is a type of cancer in which the blood-producing tissue in bone marrow produces excessive numbers of immature white blood cells, impairing the function of normal blood cells. Hairy cell leukemia is a rare form of leukemia that mostly affects men. Most patients survive for five years after diagnosis and some survive for more than ten. Magnification: x12,500 at 8x10.