Aberrant expression of myeloid antigens in patients of acute lymphoblastic leukaemia

Objective: To determine the immunophenotypic pattern and aberrant expression of myeloid antigens in newly diagnosed patients of acute lymphoblastic leukaemia(ALL). Methods: This descriptive cross-sectional study was carried out in Haematology / Pathology department, Army Medical College, National University of Medical Sciences (NUMS) in collaboration with Immunology and Haematology departments of Armed Forces Institute of Pathology (AFIP), Rawalpindi from 1st January, 2019 to 31st December, 2019. Seventy-three (73) recently diagnosed patients of Acute Lymphoblastic leukaemia of all age groups and both genders were included in the study. A proforma was used to note demographic data. CBC, cytochemical stains and bone marrow examinations were carried out and assessed for morphology and percentage of blasts using a microscope. Flow cytometry was used to perform immunophenotyping on samples of peripheral blood and bone marrow, using a standard panel. Results: The most commonly expressed markers were weak CD45, TdT, CD19, CD10 and HLA-DR. Weak CD45 was present in almost all blast cells and there was no remarkable difference in its positivity among various subtypes of ALL. Myeloid expression was observed in 13 (17.8%) cases. CD13 and CD33 were aberrantly expressed in 11 and 12.3 of all cases of ALL respectively. Conclusion: Expression of aberrant myeloid CD markers in acute lymphocytic leukaemia has prognostic significance and should be documented during lineage assignment of acute leukaemias while performing immunophenotyping.