hairy cell leukemia
Meaning of hairy cell leukemia: A slow-growing blood cancer named for the fringed look of its cells, marked by a large spleen and low counts across the board.
Definition of hairy cell leukemia
Hairy cell leukemia is a rare, slow-growing cancer of B lymphocytes, a type of white blood cell. The abnormal cells carry fine hair-like projections around their edge, which is where the name comes from. They accumulate in the bone marrow and the spleen, crowding out normal blood production, so the spleen enlarges while blood counts fall.
How does it show itself?
Through the consequences of low blood counts rather than through anything the tumor does directly. Tiredness and breathlessness come from anemia, repeated or unusual infections from a shortage of neutrophils, and easy bruising from a low platelet count. Many people notice fullness or discomfort under the left ribs from an enlarged spleen, and some are found by chance on a routine blood test. Unlike most leukemias the white cell count is usually low rather than high, and one particular cell type, the monocyte, is strikingly reduced.
How is it diagnosed?
| Test | Typical finding |
|---|---|
| Peripheral blood film | Cells with fine projections around the rim |
| Blood count | Low counts in more than one line, with very few monocytes |
| Marrow aspiration | Often a dry tap, because fibers thicken the marrow |
| Bone marrow biopsy | Cells spaced apart in a pattern likened to fried eggs |
| Flow cytometry | A characteristic combination of B cell surface markers |
| Molecular testing | A BRAF V600E mutation in the classic form |
How is it treated?
Not everyone needs immediate treatment, and disease that is causing no problems may simply be monitored. When treatment is needed, a class of chemotherapy called the purine analogs produces complete remission in the great majority, often lasting many years, given as a short course rather than as continuing therapy. Antibody treatment directed at a B cell marker and drugs aimed at the BRAF mutation are options if the disease returns. Life expectancy for many people approaches that of the general population, although relapse years later is common and further courses are usually effective.
What is it confused with?
A variant form exists that lacks the BRAF mutation, runs a more aggressive course and responds poorly to the standard drugs, so the two are separated at diagnosis. Splenic marginal zone lymphoma also produces a large spleen and marrow involvement, and other causes of leukemia with an enlarged spleen are excluded by the marker pattern.
Also known as
Used in a sentence
Flow cytometry and a BRAF V600E mutation confirmed hairy cell leukemia.
Good to know
A dry tap on marrow aspiration and a markedly low monocyte count are characteristic, and the classic form carries a BRAF V600E mutation that separates it from the more aggressive variant.
Word origin
Where “hairy cell leukemia” comes from
Leukemia joins the Greek leukos, meaning white, with haima, meaning blood; the descriptive part of the name refers to the appearance of the cells.