Leptin concentrations in the peritoneal fluid of women with ovarian endometriosis are different according to the presence of a 'deep' or 'superficial' ovarian disease

Some studies have suggested a possible role of leptin, an active cytokine produced by adipocytes, in the pathogenesis of pelvic endometriosis. The present study was designed to assess leptin levels in the peritoneal fluid (PF) of women with the 'deep' or 'superficial' types of ovarian endometriosis. Twenty-seven women with a single ovarian endometrioma having a mean diameter between 3 and 5 cm were included in the study. Patients were divided into two groups according to the type of ovarian endometriosis: Group A (n = 11) consisted of women with 'superficial' endometriomas located at the ovarian surface; Group B (n = 16) included patients with 'deep' intra-ovarian endometriomas. Women undergoing laparoscopy for unexplained infertility and not affected by pelvic and/or ovarian endometriosis were considered as controls (Group C, n = 10). Patients with an ovarian endometrioma had significantly increased PF leptin concentrations than endometriosis-free controls (Groups A and B vs. Group C, p < 0.01). Patients with 'superficial' endometriomas had significantly higher PF leptin levels compared with patients with 'deep' endometriomas (Group A vs. B, p < 0.01). This difference remained significant after correction for the BMI; moreover, a positive correlation between PF leptin and BMI was observed in Groups B and C, but not in women with 'superficial' endometrioma (Group A). Our observations suggest that: (a) leptin could play an active role in promoting the development of 'superficial' ovarian endometriomas and (b) 'superficial' and 'deep' ovarian endometriomas could have a different pathogenesis.