Old (from 1989): "Pelvic endometriosis was observed in 15 of 91 women (16.5%) with laparoscopically confirmed polycystic ovary syndrome. There were no significant clinical differences among those with and those without endometriosis. The groups were of similar age, parity, and ponderal indices and had similar incidences of oligomenorrhea, hirsutism, and infertility; the serum concentrations of LH, FSH, LH/FSH, prolactin, testosterone, and dehydroepiandrosterone sulfate were also similar in each group. However, women with polycystic ovaries and endometriosis presented more frequently with regular menses (40 versus 14.5%; P = .05) and less frequently with secondary amenorrhea (0 versus 38.2%; P = .05) and galactorrhea (0 versus 9.2%; P = .05) than the women with polycystic ovaries alone. Endometriosis appears to be a coincidental finding in polycystic ovary syndrome, and its development does not modify significantly the clinical picture or biochemical profiles of these patients. However, menstrual patterns seem to be affected." http://www.ncbi.nlm.nih.gov/pubmed/2797642
2011: "The endocrinologic and metabolic abnormalities of women with polycystic ovary syndrome (PCOS) can result in a series of endometrial diseases. Abnormalities of hyperandrogenism and hyperinsulinemia that may be found in PCOS can elevate the levels of E2 indirectly, reduce progesterone secretion and induce some growth factors such as vascular endothelial growth factor (VEGF) and insulin-like growth factors (IGFs) over expression, which may have a major impact on endometriosis occurrence and development. We suppose that there is a possible connection between PCOS and endometriosis." http://www.sciencedirect.com/.../pii/S1001784412600133