Hairy cell leukemia (HCL) is a rare cancer of the blood. It affects B cells, a type of white blood cell (lymphocyte).

HCL is caused by the abnormal growth of B cells. The cells can look "hairy" under the microscope because they have fine projections coming from their surface.

HCL can lead to low numbers of normal blood cells.

The cause of this disease is unknown. It affects men more often than women. The average age of onset is 55. Hairy cell leukemia is rare.

• Weakness
• Fatigue
• Weight loss
• Easy bruising or bleeding
• Recurrent infections and fevers
• Excessive sweating (especially at night)
• Swollen lymph glands
• Feeling full after eating only a small amount (early satiety)

During a physical exam, the doctor may be able to feel a swollen spleen or liver. An abdominal CT scan may be done to confirm this swelling.

A complete blood count shows low levels of white and red blood cells, as well as platelets.

Blood tests and a bone marrow biopsy can detect hairy cells. A test called TRAP can confirm the cancer diagnosis.

People with this disease may not need treatment in the early stages. Some patients may need an occasional blood transfusion.

If treatment is needed because of very low blood counts, a variety of chemotherapy drugs can be used. A cancer drug called interferon is also used. In most cases, chemotherapy can relieve the symptoms of the disease (put the disease into remission) for many years.

Removing the spleen may improve blood counts, but is unlikely to cure the disease. Antibiotics can be used to treat infections. People with low blood counts will receive growth factors and possible transfusions.

Newer chemotherapy treatments have greatly improved the survival of patients with hairy cell leukemia. Most patients with hairy cell leukemia can expect to live 10 years or longer with the disease.

The low blood counts caused by hairy cell leukemia can lead to infections, fatigue, and excessive bleeding.

Call your health care provider if you have significant bleeding. Also call if you have signs of infection, such as a persistent fever, cough, or general ill feeling.

There is no known way to prevent this disease.