Can malignant potential of endometrial polyps be determined by incorporating the endometrial intraepithelial neoplasia (EIN) classification?

Objective. The reported frequency of malignant or premalignant changes confined to endometrial polyps (EP) is 0.5-6%. The management of atypical endometrial hyperplasia (AEH) confined to EP is not yet established. Recently, an alternative pathological nomenclature has emerged using the term endometrial intraepithelial neoplasia (EIN) instead of atypia. The objective of this study was to evaluate the safety of conservative hysteroscopic resection of endometrial polyps with AEH or EIN. Methods. Retrospective cohort study of all cases of hysteroscopic resections of EP was performed at a single center between the years 2000-2011. All patients with a pathologic diagnosis of AEH in EP were included. A post-hoc revision of the pathologic specimens was made according to the EIN classification. Results. Of the 32 patients with AEH in EP, 25 had normal endometrial curetting. Even with AEH confined to EP, 12 cases (48%) showed AEH (11 cases) or carcinoma (1 case) in the hysterectomy specimens. EIN in EP (14 cases) was correlated with 57% of diagnosis of EIN or carcinoma in the uterus; whereas in the absence of EIN in EP only 1 of 9 cases showed EIN in the final pathologic specimen (p = 0.002), and none with carcinoma, which yields a PPV of 14% and a NPV of 100%. Conclusion. The diagnosis of EIN in EP may be a better predictor than AEH for endometrial involvement with malignant or pre-malignant neoplasms. The safety of conservative hysteroscopic resection of EP with AEH/EIN is questioned.