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Chronic Lymphocytic Leukemia

New Approaches for a Common Disease

CLL: Evolution of Diagnostic Criteria

Slide 4

October 2008

The diagnostic criteria of CLL have evolved over the last 30 years. In 1975, Rai staging for CLL emerged which also defined CLL as those cases having greater than a 15,000 absolute lymphocyte count, or ALC, in the peripheral blood. By the late 1980’s and reaffirmed in 1996 the NCI working group redefined CLL as those cases having a greater than 5,000 ALC and pointing out the necessity of having a precise immunophenotype.

Just recently the International working group  of CLL, or the IWCLL, published new criteria which now defines CLL as being those cases having greater than 5,000 B-cells of at least 3 months’ duration. Please note the change from a lymphocyte to a B-cell count.

Flow cytometry remains important in determining both clonality as well as the CLL immunophenotype. In addition the presence of cytopenias caused by a typical marrow infiltrate defines CLL regardless of the number of B-cells or the amount of nodal involvement.

Evolution of Diagnostic Criteria


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