Unravelling the Ovarian Endometrioma Pathogenesis: “The Long and Winding Road” * across the Various Theories

Abstract

Controversy exists regarding the pathogenesis of endometriotic ovarian cysts. Different and complex theories have been proposed over the years since the description of chocolate cysts by Sampson in 1921. We have herein reviewed findings in support and against the most widely accepted theories. According to the theory of Hughesdson and Brosens, a prerequisite for endometrioma formation seems to be the inversion and progressive invagination of the ovarian cortex after the accumulation of menstrual debris derived from bleeding of superficial endometriotic implants, which are located on the ovarian surface and adherent to the peritoneum. Disproving the metaplasia hypothesis put forward by Donnez and coworkers and supporting the involvement of the ovulation process in the development of ovarian endometriosis, Vercellini and colleagues have recently demonstrated that a cystic corpus luteum may be a transitory step toward endometrioma formation. As these theories are not able to explain the various aspects of endometrioma formation fully, the possibility that the coelomic metaplasia of the ovarian mesothelium with changes into typical endometrial glands and stroma might be responsible for the endometrioma formation cannot be totally ruled out. Further research is needed to clearly elucidate the pathogenetic aspects of endometriotic ovarian cysts.