Chronic lymphocytic leukemia (CLL)

Alternative names:

CLL

Definition:

A malignancy of the white blood cells known as lymphocytes, characterized by a slow progressive increase of these cells in the blood and the bone marrow.

Causes, incidence, and risk factors:

Chronic lymphocytic leukemia (CLL) affects the B lymphocytes and causes immunosuppression, failure of the bone marrow, and infiltration of malignant (cancerous) cells into organs. Usually the symptoms and the course of the disease will develop gradually. CLL occurs in the elderly with 90% of the cases in people over 50 years old. Many cases are detected by routine blood tests in people with no symptoms. The cause of CLL is unknown. No relationship to radiation, carcinogenic chemicals, or viruses has been determined. An increased incidence of CLL has been noted in people with certain autoimmune diseases. The incidence increases with age to 15 out of 100,000 by 70 years old.