後腹膜腔に発生した子宮内膜症性嚢胞の１例

抄録

　The peritoneum covering pelvic organs such as the uterine and ovarian ligaments and the pouch of Douglas is a common site of endometriosis, which is explained by the endometrial transplantation, peritoneal metaplasia, and the Müllerian remnant theories. The endometrial transplantation theory is widely accepted. We report a case of a retroperitoneal endometriotic cyst in a 44-year-old woman (gravida 4, para 2) who visited a local physician with a complaint of left lower abdominal pain and was referred to our hospital for further evaluation and treatment of a left ovarian tumor. Magnetic resonance imaging revealed a left ovarian endometriotic cyst measuring approximately 4.5 cm in size, and we performed laparoscopic left adnexectomy. Intraoperatively, the uterus appeared normal in size, and both ovaries were normal in appearance. We did not detect any endometriotic lesions in the peritoneum, in the uterine and ovarian ligaments, or in Douglas' pouch; however, a tumor (approximately 5 cm) was observed in the left broad ligament. The cyst had a thick wall, with dark brown and slightly viscous intracystic fluid. Histopathological findings were consistent with an endometriotic cyst, and the cyst wall showed fibrous tissue containing smooth muscle. Based on the classification of rectovaginal endometriosis proposed by Koninckx et al., the lesion was categorized as a Type III cyst, and metaplasia of Müllerian remnants was considered the likely pathogenetic contributor to the retroperitoneal cyst.