Cystic endometriosis originating in a subserosal myoma: A report of two cases

Introduction: Uterine myomas often occur concomitantly with endometriosis; however, few studies have reported endometriosis within a uterine myoma. We report two cases of cystic endometriosis originating in a subserosal myoma.Case 1: A 35-year-old gravida 0, para 0, with a history of endometriosis visited our hospital for evaluation of increasing lower abdominal pain. Transvaginal ultrasonography revealed an irregularly shaped, partially hyperintense mass (81 mm), and we performed laparoscopic surgery on the same day. The mass was contiguous with the posterior wall of the uterus, and we observed rupture of a hematoma within the mass and resected the lesion. Histopathological evaluation of the resected specimen revealed leiomyoma with endometriosis.Case 2: A 43-year-old gravida 0, para 0, with a history of multiple uterine myomas was admitted to our hospital's cardiology department on an emergency basis for management of cardiac tamponade and was subsequently referred to our department for evaluation of a malignant tumor. She underwent laparoscopic total hysterectomy and bilateral oophorectomy, 7 months later. Intraoperatively, we detected a subserosal myoma, which was dissected and stored in a pouch and retrieved separately from the uterus. Histopathological evaluation revealed leiomyoma with endometriosis. Cystic endometriosis originating within a subserosal myoma causes sudden abdominal pain and is often indistinguishable from ovarian tumors and sarcomas. We laparoscopically removed only the subserosal myoma separately to prevent spread of the myoma fragments. This condition can be differentiated from a subserosal myoma with dysmenorrhea and nonspecific images on magnetic resonance imaging.