SCREENING OF ENDOMETRIOID ADENOCARCINOMA AND ATYPICAL HYPERPLASIA FOR MISMATCH REPAIR GENES BY IMMUNOHISTOCHEMISTRY: A SINGLE INSTITUTE EXPERIENCE
Objective: Mutation of mismatch repair gene (MMR) is one of the proven molecular etiology of endometrioid adenocarcinoma. The aim of our study is to find frequency of MMR deficient cases by immunohistochemistry (IHC) and statistically significant clinico-pathological parameters of these cases.
Material and Methods: A cross-sectional study was carried out in Chughtai Institute of Pathology from January 2018 to August 2020. A panel of four antibodies against MLH1, PMS 2, MSH2 and MSH6 MMR proteins was applied on 62 cases.
Results: Loss of MMR protein by IHC was seen in 22 out of 62 cases (35.5%). 15 cases (24.5%) showed combined loss of MLH1/PMS2, 6 cases (9.7%) showed combined loss of MLH2 /PMS in 9.7 % and isolated loss of MSH2 was seen in 1 case (1.6%). Statistically significant relationship was found between MMR protein loss and lymphocytic response around tumor. No statistically significant relationship was found for age, FIGO grade, tumor stage and location in uterine corpus.
Conclusion: Our study showed combined loss of MMR proteins in most of the cases which supports the use of a cost effective two antibody panel instead of four antibody panel approach for screening purpose. Lymphocytic response is more commonly seen in MMR deficient cases. Young age, tumor grade, stage and lower uterine segment involvement has no relation with MMR deficient expression. Our study concludes that regardless of age, grade, stage and tumor location, all newly diagnosed cases of endometrial carcinoma should be screened for MMR status by IHC.
Key Words: Endometrioid adenocarcinoma, Mismatch repair, Screening, Immunohistochemistry.