Learn about the three most important lines of latitude on Earth - the equator, Tropic of Cancer, and Tropic of Capricorn. Learn about the three most important lines of latitude on Earth - the equator, Tropic of Cancer, and Tropic of Capricorn.
General Discussion. Hairy cell leukemia (HCL) is a rare type of blood cancer characterized by abnormal changes in white blood cells known as B lymphocytes. The bone marrow creates too many of these defective cells, known as hairy cells because of the thin hair-like projections found on their surface.
Hairy cell leukemia (HCL) 1  Is a type of blood cancer that begins in the bone marrow. 2  Is a rare type of leukemia in adults.  Hairy cell leukemia gets its name from the short, thin projections that look like hair on its cells.