Rectovaginal septum endometriosis:an immunohistochemical analysis of 62 cases

Deep infiltrating endometriosis of rectovaginal septum is a particular form of endometriosis located under the peritoneal surface. This kind of lesions are very active and strongly associated with pelvic pain symptoms. A study on 62 cases of rectovaginal septum endometriosis by means of immunohistochemistry was conducted in order to evaluate the oestrogen and progesterone receptor levels in these cases and to correlate them to the level of vascularization (CD34 expression) and the amount of nerve fibres (S100 expression). Data showed great heterogeneity in the expression of all the parameters analyzed. Nevertheless, by using Spearman correlation test to assess relationship among oestrogen and progesterone receptors, S100 and CD34 staining, a significant direct correlation was found between all the parameters analyzed. These observations sustain the hypothesis that oestrogen and progesterone play an important role in the genesis of endometriotic glands, in the vascularization and in the proliferation of nerves.Endometriosis is a gynaecological disease defined by the histological presence of endometrial glands and stroma outside the uterine cavity, most commonly implanted over visceral and peritoneal surfaces within the female pelvis, but rarely also in the pericardium, pleura and even brain (1,2). Although the exact prevalence of endometriosis in the population is not clear, the prevalence in the general female population is 6-10%; in women with pain, infertility or both, the frequency increases to 35-60% (3). Endometriosis is usually associated with infertility and pelvic pain such aschronic dysmenorrhea, intermenstrual abdominal and pelvic pain, back pain, dysuria, dyschezia and dyspareunia (1). Deep infiltrating endometriosis of rectovaginal septum is a particular form of endometriosis located under the peritoneal surface (4). These kind of lesions are very active and are strongly associated with pelvic pain symptoms (5).The mechanisms by which deep infiltrating endometriosis lesions cause pain and hyperalgesia are poorly understood. A multifactorial pathogenetic mechanism could be hypothesized, where cyclical bleeding, anatomical structure and locations of the lesions, production of prostaglandins and inflammatory mediators by the endometriosic lesions themselves and local response of the damaged tissues with production of mast cells could be outlined (6,7). Despite this, deep infiltrating endometriosis is rather poorly reflected in the R-AFS classification (8). Moreover, previous immunohistochemical analyses have demonstrated marked heterogeneity in the expression of oestrogen and progesterone receptors in endometriosis lesions from different patients with non-homogeneous results (9,10). Indeed, studies addressed to the exhaustive morphological and molecular characterization of this peculiar type of endometriosis are needed to better define the impact of rectovaginal endometriosis on the pathogenesis and clinical course of this very common disease. To further analyse this topic, a study on 62 cases of rectovaginal septum endometriosis has been conducted. The aim of the study was to determine, by means of immunohistochemistry, the oestrogen and progesterone receptor levels in these cases and to correlate them to the level of vascularization and the amount of nerve fibres.