Hairy Cell Leukemia


Hairy cell leukemia is a disease in which cancer (malignant) cells are found in the blood and bone marrow. The disease is called hairy cell leukemia because the cancer cells look "hairy" when examined under a microscope.

Hairy cell leukemia affects white blood cells called lymphocytes. Lymphocytes are made in the bone marrow and other organs. Bone marrow is the spongy tissue inside the large bones in your body.

The bone marrow makes red blood cells (which carry oxygen and other materials to all tissues of the body), white blood cells (which fight infection), and platelets (which make your blood clot). Lymphocytes also are made in the spleen (an organ in the upper abdomen that makes lymphocytes and filters old blood cells from the blood), the lymph nodes (small bean-shaped organs throughout the body), and other organs.

When hairy cell leukemia develops, the leukemia cells may collect in the spleen and the spleen swells. There also may be too few normal white blood cells in the blood because the leukemia cells invade the bone marrow, and the marrow cannot produce enough normal white blood cells. This can result in a decreased resistance to infections.


The disease usually presents in middle-aged men (average age about 55). Men are affected five times more often than women are.


Most patients present with the gradual onset of fatigue, a spleen that is larger than normal or an infection.


Your doctor will order blood tests to count the number of each of the different types of blood cells. If the results of the blood tests are not normal, you may have to have more blood tests.

Your doctor may also do a bone marrow biopsy. During this test, a needle is inserted into a bone and a small amount of bone marrow is taken out and looked at under the microscope. Your doctor can then tell what kind of leukemia you have and plan the best treatment.


Some people with hairy cell leukemia have few symptoms and may not need treatment right away. The treatment of choice is cladribine (2-chlorodeoxyadenosine; CdA), 0.14 mg/kg daily for 7 days. Cladribine is a relatively nontoxic medication that produces benefit in about 95 percent of cases, and complete remission in greater than 80 percent. Fortunately, responses seem to be long-lasting and few patients relapse in the first few years.

Treatment with interferon and by splenectomy (surgically removing the spleen) are rarely used now.