Discrepancies between DNA index by flow cytometry and cytogenetic studies in childhood B-Lymphoblastic leukemia

BACKGROUND: DNA index by flow cytometry (DNAI-FCM) is a rapid technique used in classification of acute B-lymphoblastic leukemia (B-ALL). The objective of this study is to estimate the reliability of FCM in the early classification of childhood B-ALL and to analyze the causes of discrepancies between the DNAI-FCM and the cytogenetic studies (CG) (Karyotype and Fluorescent in situ Hybridization [FISH]). MATERIALS AND METHODS: DNAI-FCM and CG (Karyotype and FISH) were analyzed in 69 consecutive children, newly diagnosed with B-ALL in King Faisal Specialist Hospital and Research Centre between January 2013 and June 2014. RESULTS: A statistically significant correlation existed between DNAI-FCM and CG ( P = 0.001). DNAI-FCM was proportional to CG in 82.6% (57/69) of the cases. There was a discrepancy between the DNAI-FCM and the CG in 17.4% (12/69) of the cases. CONCLUSION: DNAI-FCM shows 82.6% concordance with CG in childhood B-ALL with a predictive value of 81%. Discrepancies occur due to either the small size of the chromosome or due to insufficient genetic material representing the abnormality.