Hairy Cell
Hairy Cell Leukemia (HCL) is a type of Chronic Lymphocytic Leukemia (CLL). The disease is called “hairy cell” because in this subtype of leukemia the malignant lymphocytes have small projections on their surface that give the appearance of hair when one looks at a blood smear under the microscope.
The abnormal (malignant) cell in Hairy Cell Leukemia is a B-lymphocyte. This cell infiltrates the bone marrow and usually the spleen. Along with fibrosis (scar tissue), it consumes most of the bone marrow space. As a result, the patient often develops pancytopenia (decreased red cells, white cells and platelets).
Due to decreased blood counts, patients with Hairy Cell Leukemia are highly susceptible to serious infections. They are anemic and can bleed easily because of low platelet counts. They usually experience weakness and fatigue as a result of anemia. They often have splenomegaly (an enlarged spleen) and may also have hepatomegaly (an enlarged liver).
Patients who have Hairy Cell Leukemia often have reduced immunity, and a significant percentage may develop immune diseases.
The incidence of Hairy Cell Leukemia (HCL) is much less than CLL - about 0.4 cases per 100,000 population. Only about 600 new cases of HCL are diagnosed each year in the United States.
Although Hairy Cell Leukemia is too rare a subtype of leukemia to fully investigate using epidemiologic methods, a few case-control studies of hairy cell leukemia patients have been performed, and some have shown significant excesses of the disease among benzene-exposed workers.