Hairy cell leukemia

This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science

This page was updated on May 26, 2022.

Hairy cell leukemia (HCL) is a rare subtype of chronic lymphocytic leukemia (CLL) that progresses slowly. HCL is caused when bone marrow makes too many B cells (also known as B lymphocytes), a type of white blood cell that fights infection. As the number of leukemia cells increases, fewer healthy white blood cells, red blood cells and platelets are produced.

Hairy cell leukemia gets its name from the way the cells look under the microscope—with fine fragments that make them look "hairy." HCL affects more men than women, and it occurs most commonly in middle-aged or older adults. HCL is considered a chronic disease because it may never completely disappear.

Common hairy cell leukemia symptoms

Symptoms of hairy cell leukemia may include:

  • Weakness, fatigue or feeling tired
  • Fevers or frequent infections
  • Easy bruising or bleeding
  • Shortness of breath
  • Unexplained weight loss
  • Pain or a feeling of fullness below the ribs
  • Painless lumps in the neck, underarm, stomach or groin
  • Swollen lymph nodes

NOTE: These symptoms may be attributed to a number of conditions other than cancer. It is important to consult with a medical professional for an accurate diagnosis.

Diagnosing hairy cell leukemia

To diagnose hairy cell leukemia, health care providers will perform a series of tests, which may include:

  • A physical examination, including taking a family history and evaluating the patient’s overall health
  • Blood tests, including a complete blood count to measure the types of blood cells in the patient’s body
  • A CT scan to measure the size of structures including the liver, spleen and lymph nodes
  • A peripheral blood smear, which allows the care team to examine blood cells through a microscope to look for signs of classic hairy cell leukemia cells
  • A bone marrow biopsy, which allows the care team to measure the blood cells in the bone marrow
  • Flow cytometry to determine the attributes of cells in the patient’s body

Hairy cell leukemia treatments

Treatment of hairy cell leukemia may not be needed for people in the early stages of the disease. Because this cancer progresses very slowly and sometimes doesn't progress at all, treatment is often recommended only after signs and symptoms develop. The majority of patients with hairy cell leukemia eventually require treatment.

Common hairy cell leukemia treatment options include:

Chemotherapy: Anti-cancer drugs are considered the first-line treatment for HCL and are the most commonly used treatment. For most HCL patients, chemotherapy drugs may eliminate the cancer for many years.  </p">

ImmunotherapyThese drugs are designed to boost the body’s immune system to recognize and destroy the cancer.

SurgeryThe spleen helps make the body’s white cells, and hairy cell leukemia may cause an enlarged spleen (also called splenomegaly). Surgery to remove the spleen may be an option if the spleen ruptures or if it is enlarged and causing pain. A splenectomy may improve blood counts, but it is not likely to eliminate the disease.

Next topic: What are the stages of leukemia?

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