Verification of aberrant expression of CD7 in acute myeloid leukemia

Introduction Acute myeloid leukemia (AML) is an aggressive disorder characterized by accumulation of blast cells in bone marrow. The heterogeneous phenotype of AML is based on cytogenetic mutations and molecular aberrations. Immunophenotyping is a convenient method for quick and reproducible diagnosis of most hematological malignancies. The higher frequency of aberrant expression of lymphoid markers in AML may be related to environmental changes and accumulation of biological defects. The CD7, a T‑cell antigen, is expressed in a minority of patients with AML, and it is the most common aberrant marker found in AML in most studies. Aim We aimed to determine the frequency of CD7 expression in AML and to verify if this aberrant expression is true or false. Patients and methods The study included 32 newly diagnosed patients with AML. Detection of CD7 in AML was done by using an independent method to check the gene expression, namely, reverse transcriptase‑PCR, besides the usually used monoclonal antibody‑based flow cytometric measurements. Results The study revealed the frequency of CD7 expression in newly diagnosed AML cases to be 18.1% by flow cytometry. The AML cases with positive CD7 expression by flow cytometry were subjected to reverse transcriptase‑PCR to determine gene expression. All cases with positive CD7 expression by flow cytometry were found to be negative for CD7 gene expression by PCR. Conclusion This study raises a reasonable possibility of a false‑positive detection of aberrant CD7 expression in AML using immunophenotyping by flow cytometry.