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Hairy Cell Leukemia

Hairy cell leukemia (HCL)

  • Is a type of blood cancer that begins in the bone marrow
  • Is a rare type of chronic leukemia 
  • Hairy cell leukemia gets its name from the short, thin projections that look like hair on its cells.

What You Should Know

  • Many people with hairy cell leukemia live good-quality lives for years with medical care.
  • Hematologists and oncologists are specialists who treat people who have hairy cell leukemia or other types of blood cancer.
  • The drug cladribine is the initial treatment for most people who have hairy cell leukemia.
  • The 5-year event-free survival rate after treatment is approximately 90 percent of patients initially treated with cladribine. The advent of cladribine therapy has resulted in approximately an 85 percent rate of complete remission and approximately 10 percent rate of partial response.

What You Should Do

  • Ask your doctor whether a clinical trial is a good treatment option for you.
  • Talk with your doctor about your diagnostic tests and what the results mean.
  • Talk with your doctor about all your treatment options and the results you can expect from treatment.

How Does Hairy Cell Leukemia Develop?

The DNA (genetic material) of a developing stem cell in the bone marrow is damaged. This is called an “acquired mutation.”

  • Stem cells form blood cells (red cells, white cells and platelets).

This abnormal change occurs in a white cell called a B lymphocyte.

  • B lymphocytes normally produce antibodies to help fight infections.
  • Hairy cells tend to accumulate in the bone marrow, liver and spleen. Even though hairy cell leukemia affects the white cells, the lymph nodes usually don't enlarge.
  • Hairy cells multiply uncontrollably and crowd out normal white cells, red cells and platelets. 

As a result, the number of healthy blood cells (red cells, white cells and platelets) is usually lower than normal.

  • Anemia is a condition when there is a low number of red cells in the blood which can cause fatigue and shortness of breath.
  • Neutropenia is a condition when there is a low number of white cells, so the immune system can't effectively guard against infection due to a lack of neutrophils (a type of white cell).
  • Thrombocytopenia is a condition when there is a low number of platelets which can cause bleeding and easy bruising with no apparent cause.
  • Low numbers of all three blood cell counts is called pancytopenia.

Risk Factors

Doctors don't know why some cells become hairy cells and others don't. For most people who have hairy cell leukemia, there are no obvious reasons (risk factors) why they developed the disease.

Source: Hairy Cell Leukemia. Reviewed by Susan O’Brien, MD.

Helpful Resources:

The Hairy Cell Leukemia Foundation provides additional information and support for patients with hairy cell leukemia.