A Case Report of External Endometriosis in the External Hernia Sac

A 26-year-old woman treated four-years for endometriosis presented with one year of expanding left inguinal swelling painful during menstruation. Computed tomography and magnetic resonance imaging showed contrast-enhanced right ovarian cystic lesions, and left inguinal multilocular cysts, connected to the uterus by a contrast-enhanced cord. Based on a preoperative diagnosis of sliding hernia of the left ovary or the left inguinal external endometriosis, the right ovarian endometrioid cyst and the left inguinal tumor were laparoscopically excised under general anesthesia. The left internal inguinal ring was opened in an approach from the abdominal cavity. The wine-colored tumor in the hernia sac was confirmed when the inguinal canal was opened anteriorly. The tumor was resected and the hernial sac ligated at the preperitoneal fat level. The hernial hilus was closed by the Marcy method. Pathology confirmed endometriosis in the hernial sac. The woman has remained free from inguinal pain and tumor in the 12 months since surgery. We review 160 Japanese case reports on groin endometriosis. Groin hernia sac endometriosis was found only 34 cases in the Japanese literature. This example of rare external endometriosis in the groin is an excellent reminder of one of the differential diagnoses of female inguinal hernia.