Chronic Lymphocytic Leukemia
Diagnosis

Chronic lymphocytic leukemia is diagnosed through the detection of a high white blood cell count composed primarily of small lymphocytes. The diagnosis is confirmed by "immunophenotyping" (flow cytometry), which determines the types of proteins on the leukemia cells. CLL classically expresses CD19 (a B-lymphocyte protein) and CD 5 (a T-cell lymphocyte protein) simultaneously.

CLL is the one type of leukemia for which there is a formal staging system:

• RAI Stages 0 to I During this early stage of the disease, there is an elevated lymphocyte count (0) and enlarged lymph nodes (I).
• RAI Stage II In the intermediate stage the spleen becomes enlarged.
• RAI Stages III to IV In the advanced stage of the disease, bone marrow function is disturbed and there is a significant decrease in red blood cell (III) or platelet counts (IV).

The RAI stages predict survival:

• RAI Stage 0 or I More than 10 years
• RAI Stage II Six years
• RAI III or IV One to two years

New biologic markers, including chromosome abnormalities, can also help with prognosis. Having normal chromosomes, an extra chromosome 12, or a missing part of chromosome 13 are favorable; a missing part of either chromosome 11 or 17 is unfavorable.

In 5 percent to 10 percent of cases, CLL can transform to an aggressive lymphoma. This is called Richter's syndrome, and it requires lymphoma treatment.