Clinicopathological Investigation of Endometrial Polyps Following Preoperative Administration of Dienogest

Objective: To evaluate the histological influence of preoperative treatment with dienogest on the resection of endometrial polyp.Designs: Retrospective Study Setting: General hospitalMethods: We explained the study to, and obtained informed consent from, 15 patients diagnosed with an endometrial polyp between April 2008 and February 2012. Dienogest was administered orally to these women at a dose of 2 mg/day from the second day of the menstrual cycle until the evening of the day before surgery. The histological effects of dienogest were examined based on a postoperative histopathological examination.Results: Histological examination showed that the boundary between a polyp and the normal endometrium was distinct and also that the endometrial polyp showed some discriminative changes.. These included hemorrhagic erosion of the epithelial surface, atropic changes in deep glands, decreases in stromal cells, edematous accumulation in the stroma, and infiltrations, mostly by lymphocytes, findings that are rarely seen in the normal endometrium. Obvious changes in both the surface epithelium and the stroma were observed after about 7 days' preoperative administration of dienogest, whereas changes were limited to the surface area after about 14 days' treatment.Conclutions: Dienogest seems to induce an acute inflammatory reaction in the endometrial polyp after about one week of treatment, and repair occurs in the stromal area after 2 weeks. Further investigation of the appropriate duration of preoperative administration with dienogest is needed.