[B-cell] chronic lymphocytic leukemia (B-CLL, aka chronic lymphoid leukemia) is the most common type of leukemia (i.e. a type of cancer of the WBC's) in adults.

• CLL affects B cell lymphocytes, which originate in the bone marrow, develop in the lymph nodes, and normally fight infection by producing antibodies
• In CLL, B cells grow in an uncontrolled manner and accumulate in the bone marrow and blood, where it crowds out healthy blood cells. It is a disease of adults, with most (>75%) of patients Dx w/ CLL >50yo, and the majority are men. Rarely, it can occur in teenagers and occasionally children. Some of these may relate to an inherited predisposition. Most Pt’s are Dx without Sx as the result of a routine blood test that returns a high WBC count, but as it advances, it results in swollen lymph nodes, spleen, and liver, and eventually anemia and infections