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Causes and 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.

How Does Hairy Cell Leukemia Develop?

Hairy cell leukemia starts with a mutation (change) in the DNA of a single stem cell in the bone marrow. Stem cells form blood cells (white cells, red cells and platelets).

The 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. Hairy cells multiply uncontrollably and crowd out normal white cells, red cells and platelets. Even though hairy cell leukemia affects the white cells, the lymph nodes usually don't enlarge.

Hairy cell leukemia gets its name from the short, thin projections that look like hair on its cells.

If not treated, hairy cell leukemia can eventually result in serious health conditions that affect the blood:

  • anemia (too few red cells)
  • neutropenia and monocytopenia (too few neutrophils and monocytes [types of white cells], which impair the body's ability to fight infections)
  • thrombocytopenia (too few normal platelets, which causes bruising and easy bleeding)

Low numbers of all three blood cell counts is called pancytopenia.

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last updated on Wednesday, March 14, 2012

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