IMMUNOHISTOCHEMICAL STUDY ON PTEN AND CYCLIN D1 IN NON-NEOPLASTIC AND NEOPLASTIC ENDOMETRIAL LESIONS

Introduction: Endometrial carcinoma (EC) is the most common gynaecological malignancy in developed countries and has been classified into two groups, type 1 and type 2.  Type 1 or endometrioid endometrial carcinomas (EECA) accounts for 80% of EC and are thought to develop following a continuum of premalignant lesions ranging from endometrial hyperplasia without atypia (EH) and atypical hyperplasia (AH). PTEN (phosphatase and tensin homolog), a tumor suppressor gene is commonly inactivated in 83 % of endometrioid carcinoma and 55% of precancerous lesions. Cyclin D1, a cell cycle regulator is overexpressed in about 40% of endometrial carcinomas. Aim: To study the expression of PTEN (Phosphatase and tensin homolog) and Cyclin D1 in non-neoplastic and neoplastic endometrial lesions by immunohistochemistry (IHC). Methods: A 2 year cross-sectional study (September 2017 to August 2019) on 115 endometrial samples was done in the Department of Pathology, RIMS. Histomorphological features and IHC expression of PTEN and Cyclin D1 in the various endometrial lesions were studied and evaluated, data collected in IBM SPSS Statistics 21 was statistically analyzed using Chi - square  and Fisher’s Exact test. Results: Out of the 115 cases, 47(40.9%) were diagnosed as benign proliferative endometrium, 20(17.4%) benign secretory endometrium, 21(18.3%) hyperplasia without atypia, 15(13.0%)  atypical hyperplasia and 12(10.4%) endometrial carcinoma with an age group spanning from 26-68 years (mean age = 46.4).  Following IHC staining, 91.7%(11/12) and 83.3%(10/12) cases of EC and 80%(12/15) and 73.3%(11/15) cases of AH showed complete loss of PTEN expression and Cyclin D1 overexpression, respectively when compared to other benign lesions and was statistically significant  (p < .001). Conclusion: Loss of PTEN and Cyclin D1 overexpression was seen in a significant number of EECA and AH, suggesting both as an early event in endometrial carcinogenesis. Therefore, we propose the use of PTEN and Cyclin D1 immunostaining as an adjunct to histopathological diagnosis as it may be informative in the identification and further management of  premalignant endometrial  lesions that are likely to progress to carcinoma Keywords: PTEN, Cyclin D1, endometrial hyperplasia, endometrial carcinoma, endometrioid endometrial carcinomas.