Chronic Lymphocytic Leukemia (CLL)

Chronic Lymphocytic Leukemia is diagnosed by examination of peripheral blood for morphological abnormal lymphocytes; small lymphocytes with clumped chromatin and scant cytoplasm, and flow cytometry. The monoclonal B-cell population must to be > 5 x 10^9/L expressing CD5+, CD23+, CD200+ and CD43+, loss or very weak expression of CD22 or CD79b and dim expression of CD20 and surface Ig are also very often seen; this helps differentiate CLL from other lymphoproliferative disorders.
If the limit for 5 x 10^9/L can not be met, MBL should be diagnosed. “Low-count” MBL, defined as a PB CLL count of < 0.5 x 10^9/L, must be
distinguished from “high-count” MBL (> 0.5 – < 5.0 x 10^9/L).