Chronic lymphocytic leukemia displays a characteristic patterns of surface antigen expression (CD antigens), which facilitate their identification and proper classification and hence play an important role in instituting proper treatment plans. Multiparameter flow cytometric analysis has become commonplace in most laboratories for that purpose. Distinction between lymphoid and myeloid leukemias and of various subtypes of chronic lymphoproliferative disorders is crucially important. Several advances in flow cytometry, including availability of new monoclonal antibodies, improved gating strategies, and multiparameter analytic techniques, have all dramatically improved the utility of flow cytometry in the diagnosis and classification of leukemia.
Flow cytometery is very helpful in a diagnosis of any leukemic condition and can be diagnostic of CLL by showing CD5 positivity, especially when joined with CD19 and 20 in a multigated analysis. Flow cytometery represents one of several sources of information that go into making a secure diagnosis. It should not be relied on in isolation to make a diagnosis.
The role for cytogenetics once CLL is diagnosed in more complex. It can support the diagnosis by confirming abnormalities tyoical of CLL and also can provide prognostic information. A recent European guideline says: “Molecular cytogenetic analysis via fluorescent in situ hybridization (FISH) for the detection of unfavourable prognostic factors like deletions on chromosome 17p or 11q is recommended as a diagnostic procedure prior first-line treatment. The usage of unmutated VH status, VH 3.21 usage, ZAP70- and CD38 expression, serum markers like CD23, thymidine kinase and ß2-microglobuline for routine assessment is not advised. Further clinical trials are requested to standardize these prognostic markers and develop them to useful instruments in clinical practice.”
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