The relative DNA content of peripheral blood cells from 79 cases with lymphoid leukemias was analyzed by a dual-parameter flow cytometric analysis. The leukemia samples corresponded to: chronic lymphocytic leukemia (CLL) 40, CLL with more than 10% prolymphocytes (CLL/PL) 12, CLL mixed 9, prolymphocytic leukemia (PLL) 5, and B-cell lymphoma in leukemic phase 13. DNA aneuploidy was found overall in 26 (32.9%) of the cases and these corresponded to: 7 (17.5%) with CLL, 7 (58.3%) with CLL/PL, 4 (44.4%) with CLL mixed, 2 (40%) with PLL and 6 (46.2%) with B-cell lymphoma. There was a good correlation between DNA content and cytogenetics/fluorescent in situ hybridization in all but 2 cases as follows: 6 of 7 cases with diploid DNA had normal karyotype and only one had trisomy 12: 4 of 6 cases with hyperdiploid DNA had trisomy 12, one had tetraploidy and only one had a normal karyotype. Two cases were hypodiploid both by DNA and cytogenetic analysis. Our findings demonstrate a higher incidence of DNA aneuploidy in B-cell lymphoma in leukemic phase, PLL, and atypical CLL in comparison with typical CLL and a good correlation with cytogenetics. We conclude that flow cytometric DNA analysis represents a useful, sensitive, and rapid method to detect and monitor minimal changes of DNA content in leukemic lymphocytes without the need of short-term cultures.

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