In recent years, laparoscopic surgery has become the gold standard in the management of presumed benign adnexal masses. As preoperative selection is not perfect, some cases of ovarian malignancy are encountered at laparoscopy, during the management of adnexal masses presumed to be benign. We report the case of a 45-year-old lady with endometriosis, who presented with a pelvic abscess 6 months after the treatment of an endometrioma managed at another unit. She subsequently underwent a laparoscopic salpingo-oophorectomy. The histology returned showing an endometrioid adenocarcinoma of the ovary. We review the literature regarding the use of laparoscopy for ovarian masses, especially in the case of ovarian endometrioma in the perimenopause. Though conservative surgical management of endometriomas in young women is advocated by some authors, this article highlights the possible pitfalls in the management of endometriomas in women over the age of 40 years, as endometriomas can be associated with an increased risk of endometrioid and clear-cell adenocarcinoma of the ovary.