Criteria For Diagnosis

The National Cancer Institute (NCI) sponsored a working group in 1988 that developed criteria and guidelines for clinical protocols, as well as general-practice recommendations for patients with CLL.3 In 1996, the criteria and guidelines were revised to those in current use.4 These guidelines importantly include indications for treatment and criteria for evaluating response to treatment. The diagnosis of CLL requires a sustained absolute lymphocytosis of greater than 5000 lymphocytes/^L. This value is also important for making the academic distinction between CLL and small lymphocytic lymphoma (SLL), in which the absolute lymphocyte count is less than 5000 lymphocytes/^L. Patients with greater than 55% prolymphocytes on differential or greater than 15,000 prolymphocytes/^L meet the diagnostic criteria for prolymphocytic leukemia (PLL). Morphologic assessment and flow cytometry immunophenotyping are critical to confirming the diagnosis of CLL and will be discussed subsequently in this chapter.

Although a bone marrow aspirate and biopsy are not required for making the diagnosis of CLL, if performed, the aspirate smear should show greater than 30% of nucleated cells to be lymphocytes according to the NCI criteria.4 Evaluation of the sectioned bone marrow core biopsy will identify the pattern of involvement, which has prognostic value. As the bone marrow is always involved and is the last to be cleared with standard chemotherapy, a bone marrow exami nation is most helpful in evaluating response to treatment and is required to confirm complete remission. A bone marrow aspirate and biopsy are also useful in evaluating patients with thrombocytopenia to differentiate between an autoimmune process and lack of platelet production due to CLL marrow infiltration.

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