A 3-Year Retrospective Analysis Comparing Flow Cytometry-Based DNA Ploidy (DNA Index) to Conventional Cytogenetics in Paediatric Patients Diagnosed with B-cell Acute Lymphoblastic Leukaemia

Abstract

Flow cytometric analysis is a valuable tool in the diagnostic work-up of patients with B-cell acute lymphoblastic leukaemia. Flow cytometry is commonly employed to assign the DNA index (an evaluation of leukaemic ploidy status) and the immunophenotypic profile of the blasts. This retrospective data analysis compared the DNA index to conventional cytogenetics to determine the clinical utility in accurately predicting ploidy states and examined the relationship between ploidy states and immunophenotypic profiles in the local patient population. The DNA index displayed poor sensitivity, specificity and predictive values and was deemed to not be a reliable indicator of the ploidy status as it is currently interpreted. Changes to definitions of the ploidy states improved the performance of the test and are a key factor in improving the utility of the assay. Brighter expression of CD34 and CD123 were noted in the cytogenetically hyperdiploid group, in keeping with the international literature. However, the decreased expression of CD45 and brighter expression of CD20 typically described were not appreciated. Further studies with larger numbers and more in-depth cytogenetic analysis are needed to clarify the role of the DNA index in the local patient population.