June 1st 2007
Chronic lymphocytic leukemia (CLL) is a clonal malignancy that results from expansion of the mature lymphocyte compartment. This expansion is a consequence of prolonged cell survival, despite a varied cell turnover. The affected lymphocytes are of B-cell lineage in 95% of cases, and the remaining cases involve T lymphocytes, representing a distinct disorder. CLL is the most common leukemia in adults in Western countries, accounting for approximately 25%-30% of all leukemias. The proportion of cases diagnosed with the early stages of the disease (Rai stage 0) has risen from 10% to 50%, probably because of earlier diagnosis (routine automated blood counts).