The contribution of PAX2 and PAX8 expression in endometrial hyperplastic lesions and endometrial malignant tumors in histopathological diagnosis and classification

Introduction: Endometrial carcinomas typically develop from endometrial hyperplasia caused by the effects of unopposed estrogen. To date, for the right clinical assessments of endometrial hyperplasia, various classifications were used and various methods of distinguishing these lesions have been used. In our study, we aimed to test whether PAX2 and PAX8 showed a significant change in the spectrum from atrophic endometrium to the endometrioid tumors. Materials and Methods: PAX2 and PAX8 immunohistochemical stains were studied in tissue samples of 10 proliferative endometrium, 10 atrophic endometrium, 11 disordered proliferative endometrium, 38 endometrial hyperplasia and 51 endometrioid adenocarcinoma cases between 2010 and 2015 years. Results: The highest PAX2 and PAX8 expression averages were found in the normal endometrium (98.20% and 98.00%, respectively) and the lowest in endometrioid adenocarcinoma (7.01% and 60.80%, respectively). In the spectrum extending from the normal endometrium to the tumor, there was a decreasing expression of PAX2 and PAX8. There was no significant correlation between the expression rate and intensity of PAX2 and PAX8 with Ki-67, p53 expression, histological grade and other prognostic factors as depth of myometrial invasion, lymphovascular invasion, cervical involvement, lymph node (p> 0,005). Conclusion: Recently, the expression of PAX2 and PAX8 proteins in gynecological malignancies has become a subject of curiosity, and various studies have been applied in this respect. In most studies, PAX2 has been reported to show low expression in endometrial carcinomas, such as PTEN, but in some publications established that high PAX2 expression. PAX8 protein has been mostly reported about demonstrating the primer müllerian origin but it has not been studied enough about the expression pattern in endometrial preneoplastic and neoplastic lesions. Further studies are needed to demonstrate the utility of PAX2 or PAX8 in identifying and classifying preneoplastic and neoplastic lesions of the endometrium. Keywords: Endometrial hyperplastic lesions, endometrial malignant tumors, PAX2, PAX8