Introduction:
In 2016, WHO gave a comprehensive classification system that included morphology, immunophenotyping, molecular and genetic findings. Flow cytometric immunophenotyping is the backbone of WHO classification, helping to make a more accurate and faster diagnosis.

Aim:
This study has been conducted to find immunophenotyping aberrancy of acute leukemia (AL) and its association with gender and age group.

Material and methods:
This is a descriptive retrospective study of 1012 AL patients diagnosed between January 2011 and January 2019, including all new patients of all ages and both sexes, who had available immunophenotyping data.

Results and discussion:
The most common aberrant antigen on acute myeloid leukemia (AML) was CD7, on precursor B lymphoblastic leukemia (B-ALL) was CD33 and on precursor T lymphoblastic leukemia (T-ALL) was CD13. There was no association between sex/age and antigen aberrancy except a significant increase in CD34 loss on pre B acute lymphoblastic leukemia (pre B-ALL) and HLA-DR expression on acute promyelocytic leukemia (APL) in males compared to female patients and an increase of CD19 expression on non-APL-AML and an elevation of CD34 loss on T-ALL in adult compared to pediatric patients. Not only detection of aberrant expression of CD markers in leukemic cells helps to estimate molecular abnormalities and has a prognostic effect, but also a specification of neoplastic cell markers at the time of diagnosis is essential for monitoring patients after treatment.

Conclusions:
Although in this study, no association between sex/age and aberrancy of antigens was detected (except in certain AL subtypes), AL specific immunophenotype is essential for minimal residual disease detection.