Biclonal chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is well characterized clinically and imm unophenotypically. Demonstration of a monotypic CD19+, CD5+ B-cell populati on is central to the diagnosis. We report 2 cases of biclonal CLL. Two elde rly man were encountered with an absolute lymphocytosis consisting of the t ypical CD5+, CD19+, CD23+ B-cell population seen in CLL; however, immunoglo bulin light chain restriction by flow cytometry was not apparent as B cells expressed kappa or lambda light chains without a clear monotypic populatio n. Molecular genetic analysis of flow cytometry-sorted cells (kappa and lam bda populations) revealed in both cases 2 monoclonal B-cell populations. Th e characterization of these cases and a review of the issues surrounding bi clonal CLL are presented.