Role of Immunohistochemistry in Diagnosis and Subtyping of Acute Leukemia using Selected IHC Markers in a Resource Limited Setting

Abstract

Introduction: In resource limited settings where genetic studies and flow cytometry were not routinely done or available, morphology is primarily used for diagnosis and subtyping of acute leukemias with use of ancillary tests like cytochemistry and immunohistochemistry in selected cases for a more accurate and definitive diagnosis. This study was done to assess the role of immunohistochemistry in diagnosis and subtyping of acute leukemias in resource poor setting using selected IHC markers and to find diagnostic accuracy of morphologic diagnosis. Material and methods: The study was done on 45 selected cases of acute leukemia. Immunohistochemistry was done on all cases for typing and confirmation of diagnosis after morphological examination of peripheral blood smears and all three bone marrow preparations.A limited panel of IHC markers were used including Anti MPO, Anti CD3, Anti CD20, Anti CD22, Anti TdT, Anti CD117, Anti CD15 and Anti CD68(KP1) for immunohistochemistry. Results: The accuracy of morphological diagnosis in cases of AML and ALL in the study was 84.09% and 82.22% respectively. By intercalating immunohistochemical studies with morphological examination almost all cases of acute leukemia can be diagnosed and subclassified, and diagnostic accuracy is increased as compared to morphological examination alone. Conclusion: Though morphology remains the gold standard for paraffin embedded bone marrow trephines,immunohistochemical staining has became an integral part of diagnostic workup in cases of hematologic malignancies in limited resource settings.