Immunophenotypic patterns and aberrant antigen expression in acute leukemia: A retrospective flow cytometry study of 240 patients

BACKGROUND: Acute leukemia is the heterogeneous group of malignancies with various clinical, morphological, immunophenotypic, genetic, and molecular features. Multiparameter flow cytometry is the most important method allowing for lineage assignment in acute leukemia and detection of aberrant antigen expression. OBJECTIVES: The aim of this study was to characterize the immunophenotypic profiles of acute leukemia patients analyzed at a single private medical laboratory and to evaluate the distribution of leukemia subtypes, aberrant antigen expression patterns, and demographic correlations. MATERIALS AND METHODS: This retrospective study analyzed flow cytometry data from 240 acute leukemia cases (110 AML, 126 ALL, 4 Undifferentiated and Biphenotype acute leukemia) diagnosed at AmrLab Medical Laboratories between January 2018 and August 2025. Immunophenotyping was performed using an 8-color BD FACS Canto II flow cytometer with extensive antibody panels, including myeloid markers (CD13, CD33, CD117, MPO, CD34, and HLA-DR) and lymphoid markers (CD19, CD10, CD79a, cCD3, and CD7). RESULTS: The cohort comprised 240 patients with nearly equal AML (47.5%) and ALL (52.5%) distribution. The median age was 37 years for AML (range 1-95) and 10 years for ALL (range 1-64). Male predominance was observed (male: female ratio 1.38:1). AML-M1 was the most common AML subtype (27.2%). B-ALL (CD10+) constituted 78.6% of ALL cases. The key findings included the high expression of CD13 (92.9%) and CD33 (84.8%) in AML and CD79a (87.3%) and CD19 (87.1%) in B-ALL. Aberrant antigen expression was detected in 22.6% of AML cases (CD7+) and 10.5% of ALL cases (CD13+). CONCLUSION: This study provides comprehensive immunophenotypic characterization of acute leukemias, demonstrating characteristic marker expression patterns and significant aberrant antigen expression frequencies and may inform diagnostic and prognostic approaches.