STEREOMETRIC EVALUATION OF PERITONEAL ENDOMETRIOSIS AND ENDOMETRIOTICNODULES OF THE RECTOVAGINAL SEPTUM

A computerized morphometrical investigation was performed on endometri otic tissue from the peritoneum (n = 225) and rectovaginal nodules (n = 65) to compare histologically and stereologically the rectovaginal s eptum endometriotic nodule to peritoneal endometriosis. Mitotic activi ty, stromal vascularization and the epithelium/stroma ratio were found to be significantly different in peritoneal and rectovaginal endometr iosis, The evaluation revealed a major role of glandular epithelium in rectovaginal nodules where the stroma sometimes appeared absent aroun d glandular epithelium. The study demonstrated opposite effects of gon adotrophin-releasing hormone agonists (GnRHa) and lynestrenol on the t wo lesions, Indeed, in peritoneal endometriosis, after GnRHa therapy, our study demonstrated a lower rate of mitosis and poor stromal vascul arization. The same drug was unable to induce the same effects in the nodule although, in contrast, lynestrenol has a strong effect on nodul e vascularization. In conclusion, it is suggested that the rectovagina l adenomyotic nodule is a specific disease, different from peritoneal endometriosis. It is not the consequence of 'deep infiltrating' endome triosis but can probably develop from Mullerian rests present in the r ectovaginal septum.