Hairy cell leukemia

Encyclopedia of Medicine, Apr 06, 2001 by Lata Cherath

Hairy cell leukemia is a disease in which the cells that are present in the blood and bone marrow turn abnormal or cancerous. It is called "hairy cell leukemia" because the cells have tiny "hairy" projections when examined under the microscope.

Hairy cell leukemia is a rare cancer. There are approximately 600 new cases diagnosed every year in the United States. The disease commonly affects older people, with the average age at diagnosis being 50 years. The disease is four times more common in men.

There are three types of cells found in the blood: red blood cells that carry oxygen to all the parts of the body; the white blood cells which are responsible for fighting infection and protecting the body from diseases; and platelets which help in the clotting of blood. Hairy cell leukemia affects the white blood cells called lymphocytes. The lymphocytes are made in the bone marrow, spleen, and the lymph nodes.

When hairy cell leukemia develops, the white blood cells become abnormal and accumulate in the spleen, causing it to become enlarged. The cells may also collect in the bone marrow and stop it from producing blood cells. As a result there may not be enough normal white blood cells in the blood to fight infections.

The cause of hairy cell leukemia is not known. It is a slowly progressing disease and the patients may not show any symptoms for many years. As the disease advances, the patients may have an enlarged spleen, because of the accumulation of the abnormal cells in the spleen. The liver may at times become enlarged. The blood tests may show abnormal counts of all the different types of cells. This happens because the cancerous cells invade the bone marrow as well and prevent it from producing normal blood cells. Because of the low white cell count in the blood, the patient may have frequent infections. Fever accompanies the infections. There may also be other symptoms such as unexplained weight loss, fatigue, and night sweats. The low red cell count may cause anemia, and the low platelet count may cause the person to bruise easily.

If a patient complains of fatigue and has recurrent infections, and if the spleen is enlarged, the doctor may order several blood tests. In these tests, the total numbers of each of the different types of blood cells (CBC) are reported. If the blood tests are abnormal, the doctor may order a "bone marrow biopsy". During this procedure, a needle is inserted into the bone and a small amount of marrow is withdrawn for microscopic examination. This test will help the physician in identifying the type of leukemia and planning the treatment.

Some people with hairy cell leukemia have very few or no symptoms at all and may not need any treatment. If the spleen is enlarged, it may be removed in a surgical procedure known as splenectomy. This usually causes a remission of the disease.

Chemotherapy and bone marrow transplantation are rarely used in the treatment of hairy cell leukemia. Modern therapy relies heavily on the use of 2CDA (cladribine, pentastatin, fludarabine, interferon).

Biological therapy or immunotherapy, where the body's own immune cells are used to fight cancer is also being investigated in clinical trials for hairy cell leukemia. A substance called interferon that is produced by the white blood cells of the body has shown some promise in treating the disease and is being investigated further.

Most patients have excellent prognosis and can expect to live ten years or longer. The disease may remain silent for years with treatment.

Since the cause for the disease is unknown and there are no specific risk factors, there is no known prevention.

• Books
• Dollinger, Malin. Everyone's Guide to Cancer Therapy. Somerville House Books Limited, 1994.
• Morra, Marion E. Choices. Avon Books, October 1994.
• Murphy, Gerald P. Informed Decisions: The Complete book of Cancer Diagnosis, Treatment and Recovery. American Cancer Society, 1997. Organizations
• American Cancer Society (National Headquarters). 1599 Clifton Road, N.E. Atlanta, Georgia 30329. (800) 227-2345; http://www.cancer.org.
• Cancer Research Institute (National Headquarters). 681, Fifth Avenue, New York, N.Y. 10022. (800) 992-2623. http://www.cancerresearch.org.
• Hairy Cell Leukemia Research Foundation. 2345 County Farm Lane, Schaumburg, IL 60194. (800) 693-6173.
• Leukemia Society of America, Inc. National Office, 600 Third Avenue, 4th Floor, New York, NY 10016. (800) 955-4LSA.
• National Cancer Institute. 9000 Rockville Pike, Building 31, room 10A16, Bethesda, Maryland, 20892. (800) 422-6237. http://wwwicic.nci.nih.gov.
• Oncolink. University of Pennsylvania Cancer Center. Website: http://cancer.med.upenn.edu. Other
• NCI/PDQ Patient Statement, "Hairy cell leukemia." National Cancer Institute.