Diagnostic Utility of Immunophenotyping by Flow Cytometry for Diagnosis and Classification of Acute Leukemias in Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia

Background: Immunophenotypic characterization of acute leukemia is an important clinical application of flow cytometry and has become a powerful tool contributing to proper diagnosis and classification. The aim of this study is to phenotype and classify acute leukemias by flow cytometry using commonly used markers for leukemia diagnosis.Methods: A total of 40 pediatric and adult patients diagnosed with acute leukemia were evaluated by flow cytometry with 17 surface and cytoplasmic markers known to be useful in discriminating different types of acute leukemia. These results were compared with classification results using standard morphological criteria.Results: 21 of 40 patients (52.5%) were classified as acute myeloblastic leukemia (AML) while 19 (47.5%) were identified as acute lymphoblastic leukemia (ALL). Of all the ALL cases, 10 of the 19 (52.6%) were B-ALL and 47.4% (9/19) were T-ALL based on flow cytometry. Markers of immaturity HLA-DR and CD34 antigens were co-expressed in 61% of AML cases and 33% of T-ALL cases, whereas CD34 was expressed in 50% of the B-ALL cases. cMPO and CD13 were the most expressed markers of AML, CD19 and cCD79a were present in all cases of B-ALL, and cytoplasmic CD3 and CD7 were positive on most all T-ALL cases. Discrimination of AML from ALL patients by flow cytometry was 80% concordant with traditional morphology. Notable discrepancies occurred in cases where leukemia cells expressed markers for more than one lineage.Conclusions: In the Ethiopia setting, flow cytometry represents a feasible and promising adjunctive diagnostic approach for acute leukemia.