Morphological diagnosis of endometrial intraepithelial neoplasia and expression of PTEN

Objective To investigate the diagnostic applications of endometrial intraepithelial neoplasia (EIN), and the expression of PTEN in endometrial lesions.Methods Fifty-one cases of endometrial lesions were enrolled in this study.Using diagnostic criteria of EIN, the diagnosis were made and compared with the original results, Immunohistochemistry for PTEN was performed in all cases.Results Two cases of simple hyperplasia originally diagnosed were reclassified as EIN.Three cases with atypia originally diagnosed showed no EIN pattern.PTEN deletion rates were 50.0%, 50.0%, 66.7% and 81.8% in proliferative endometrium, benign hyperplasia, EIN and endometrial carcinoma, respectively.Conclusions Diagnosis of EIN is applicable and its morphology and diagnostic criteria are different from the classical one (WHO94) for endometrial hyperplasia.Detection of PTEN deletion by immunohistochemistry is useful in identifying EIN, but cannot be used as an ultimate confirming factor. Key words: Endometrial hyperplasia;  Endometrial neoplasms;  Carcinoma, endometrioid;  PTEN phosphohydrolase