PERITONEAL ENDOMETRIOSIS AND ENDOMETRIOTIC NODULES OF THE RECTOVAGINAL SEPTUM ARE 2 DIFFERENT ENTITIES

Objective: To compare histologically and stereologically the endometri otic nodule of the rectovaginal septum to peritoneal endometriosis. De sign: Morphometric investigation, cytokeratin and vimentin content, an d steroid receptor evaluation were performed on endometriotic tissue f rom the peritoneum (n = 52) and rectovaginal nodules (n = 68). Setting : An academic teaching hospital. Patients: Biopsies were takes from 12 0 patients undergoing a laparoscopy for infertility and of pelvic pain (52 from typical black peritoneal endometriotic implants and 68: from endometriotic nodule of the rectovaginal septum). None of the patient s were treated. Results: Mitotic activity was found to be significantl y different, in peritoneal and rectovaginal endometriosis. The evaluat ion suggested that the stroma is not mandatory for the invasion of gla ndular epithelium in the rectovaginal nodule, which is, like a adenomy oma, a circumscribed nodular aggregate of smooth muscle and glandular elements. Cytokeratin and vimentin content as well as the estrogen rec eptor (ER) and P receptor (PR) content were significantly lower in bot h types of lesion when compared with eutopic endometrium. But vimentin immunoreactivity in epithelium. as well as the ER and PR content, wer e significantly lower in nodules when compared with black peritoneal l esions. Conclusion: It is suggested that the rectovaginal endometrioti c nodule is a different disease from peritoneal endometriosis and must be called rectovaginal adenomyosis or rectovaginal adenomyoma. Its hi stopathogenesis probably is not related to the implantation of regurgi tated endometrial cells but to the metaplasia of Mullerian rests.