CD34 Positivity and Aberrant Marker Expression by Blasts of B-ALL Patients

Background: Acute leukemia, specifically Acute lymphoblastic leukemia (B-ALL), poses significant diagnostic and therapeutic challenges due to its complex biology and varied antigen expression.Objective: the study aims to analyze CD34 expression prevalence in patients with B-ALL at Shefaa Al-orman oncology hospitals (SOH & SOCCH), Luxor, Egypt, and explore its correlation with other aberrant antigen expressions, molecular and cytogenetics findings.Methods: A total of 73 B-ALL cases underwent immunophenotyping using flow cytometry, with standard panel including CD34, CD13, CD33, CD117, CD7 and CD66 markers, alongside molecular and cytogenetic analyses.Results: CD34 expression was observed in 93.1% of patients, with notable co-expression of CD66 and CD13. Cytogenetics tests identified chromosomal abnormalities, including Philadelphia chromosome presence in 6.1% (4/66) of cases and 4.5% (3/66) of cases in MLL gene rearrangement KM2TA 11q23.3. Molecular testing showed that, within the CD34-positive group, 98.27% (57/62) were negative for the t(4;11) (MLL-AF4) translocation. While, 10.4% (5/69) exhibited the t(1;19) (E2A-PBX1) translocation, and 12% (6/71) revealed the t(12;21) (TEL-AML1) translocation.Conclusion: Cytogenetic and molecular abnormalities study, in our patients, showed that cases with any of the aberrant marker expression have lower percentage of genetic abnormalities. Similar findings were found when comparing CD66 aberrant expression with genetic abnormalities (ρ=0.01). Further studies on larger sample size will provide better understanding of the biology of the disease.