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Hairy cell leukemia

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

Causes of Hairy cell leukemia

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

HCL usually leads to a low number of normal blood cells.

The cause of this disease is unknown, although certain genetic changes (mutations) in the cancer cells have been found. It affects men more often than women. The average age of diagnosis is 55.

Hairy cell leukemia Symptoms

Symptoms of HCL may include any of the following:

  • Easy bruising or bleeding
  • Excessive sweating (especially at night)
  • Fatigue
  • Feeling full after eating only a small amount
  • Recurrent infections and fevers
  • Pain or fullness in the upper left belly
  • Swollen lymph glands
  • Weakness
  • Weight loss

Tests and Exams

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

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

Blood tests and a bone marrow biopsy can detect hairy cells.

Treatment of Hairy cell leukemia

Treatment may not be needed for the early stages of this disease. Some patients may need an occasional blood transfusion.

If treatment is needed because of very low blood counts, chemotherapy drugs can be used.

In most cases, chemotherapy can relieve the symptoms for many years. (When the signs and symptoms go away, you are said to be in remission.)

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, possibly, transfusions.

Prognosis (Outlook)

Most patients with hairy cell leukemia can expect to live 10 years or longer after diagnosis and treatment.

Potential Complications

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

When to Contact a Health Professional

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.

Prevention of Hairy cell leukemia

There is no known way to prevent this disease.


Hasserjian RP. Hairy cell leukemia. In: Jaffe ES, Harris NL, Vardiman JW, et al., eds. Hematopathology. Philadelphia, PA: Elsevier Saunders; 2010:chap 15.

National Cancer Institute: PDQ Hairy Cell Leukemia Treatment. Bethesda, MD: National Cancer Institute. Date last modified 02/28/2014. Available at Accessed May 29, 2014.

National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines): Non-Hodgkin's Lymphomas. Version 2.2014. Available at Accessed May 29, 2014.

Related Images

Review Date: 5/29/2014
Reviewed By: Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
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Further information

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