Endometrial carcinoma of endometrioid histology is frequently preceded by endometrial hyperplasia, from which localized, premalignant lesions called endometrial intraepithelial neoplasia (EIN) emerge. Diagnostic criteria for EIN have been developed by histopathologic correlation with clinical outcome, molecular changes, and objective computerized histomorphometry. However, several benign mimics of EIN continue to cause diagnostic confusion