Possible Role of PTEN Expression in Discriminating Benign Endometrial Hyperplasia from Atypical Hyperplasia/Endometrial Intraepithelial Neoplasia in a Series of Egyptian Patients

Background: Endometrial hyperplasia represents a heterogeneous group of lesions in response to the unopposed growth-promoting action of estrogen. WHO classified endometrial hyperplastic lesions into Benign Hyperplasia (BH) and atypical hyperplasia/ endometrial intraepithelial neoplasia AH/EIN. Phosphatase and tensin homolog (PTEN) is one of the earliest and most common genetic abnormalities detected in endometrioid adenocarcinoma (type I) and even in its precursors. This study aims at histological evaluation of hyperplastic endometrial lesions according to WHO 2014 and investigates the role of PTEN expression in highlighting the precancerous group (AH/EIN). Patient and Methods: This study included a series of 70 Egyptian patients who suffered from hyperplastic endometrial lesions. They were previously diagnosed according to WHO 1994 schema simple endometrial hyperplasia without atypia (n=18), simple endometrial hyperplasia with atypia (n=2), complex hyperplasia without atypia (n=25), complex hyperplasia with atypia (n=5) and hyperplastic endometrial polyps (n=20). Results: Cases were histologically re-evaluated according to WHO 2014 classification; BH (62 cases) and eight cases of AH/EIN. A significant difference in PTEN expression (regarding percentage and intensity of staining) in relation to histopathological diagnosis was detected (P-value 0.02 and <0.05, respectively). The sensitivity and specificity of the absence of diffuse PTEN protein expression (>50%) to detect AH/EIN were 100% and 77.4%, respectively. Conclusion: Diffuse, dim or loss of immunohistochemical expression of PTEN protein is significantly correlated with the new WHO classification segregation of AH/EIN as precancerous lesions. However, further studies are recommended to confirm this association.