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Diagnosing hairy cell leukemia usually involves a series of tests, including blood tests and bone marrow tests.

Blood Tests

Your doctor needs to test your blood to help make a diagnosis. Your blood is sent to a lab for a complete blood count (CBC), which shows the number of red cells, white cells and platelets in your blood. If you have hairy cell leukemia, you'll have lower than normal levels of red cells, platelets and normal white cells. Occasionally, the blood contains many hairy cells, which increases the total white cell count. However, levels of white cells called neutrophils and monocytes are still extremely low.

Bone Marrow Tests

Your doctor or oncologist (cancer specialist) tests your bone marrow. Bone marrow testing involves two steps usually done at the same time in a doctor's office or a hospital:

  • A bone marrow aspiration to remove a liquid marrow sample
  • A bone marrow biopsy to remove a small amount of bone filled with marrow

Lab Tests to Confirm a Diagnosis

A hematopathologist examines samples of your blood and marrow to confirm a diagnosis. A hematopathologist is a specialist who studies blood cell diseases by looking at samples of blood and marrow cells and other tissues.

Hairy cells can be hard to find in the blood but can often be identified with careful searching. The hematologist stains dried marrow cells under a lighted microscope to identify whether hairy cells are present. The marrow cells often have a characteristic pattern to them. However, a firm diagnosis requires immunophenotyping performed on the blood or marrow cells. Immunophenotyping looks for a characteristic marker (antigen) on the surfaces of lymphocytes to determine if they form a certain pattern that indicates hairy cell leukemia. Flow cytometry is one type of test used for immunophenotyping.

Imaging Studies

You may need to undergo imaging studies to determine the extent of your disease. Your doctor may order an ultrasound to see the precise size of your spleen. Once your therapy begins, you may need to undergo follow-up imaging tests so your doctor can see whether the size of your spleen, liver or lymph nodes have decreased in response to treatment.

Only about 5 percent to 10 percent of hairy cell leukemia patients have enlarged lymph nodes (lymphadenopathy) when they're diagnosed. People whose disease is more advanced or who have a relapse (your cancer returns after remission, the period of no evidence of the disease) may have enlarged lymph nodes in their stomach area (abdominal lymphadenopathy). Your doctor may check your lymph nodes with a computed tomography (CT) scan during the course of managing your disease.

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