Laparoscopically resected mesothelial cyst mimicking a urachal cyst

Abstract

Objective: To report a rare case of a mesothelial cyst in the lower abdominal extraperitoneal space, mimicking a urachal cyst.
Case: A 43-year-old nulligravid female complained of lower abdominal pain, ongoing for about 6 months. Physical examination revealed a pelvic mass reaching the height of the umbilicus. Magnetic resonance imaging showed a 15 × 6 cm cystic tumor in addition to a uterine leiomyoma and an ovarian endometriotic cyst. Laparoscopic surgery revealed that the huge cystic tumor extended into the lower abdominal extraperitoneal space, similar to a urachal cyst, and was adherent to the ovarian endometriotic cyst. The resected tumor was diagnosed pathologically as a mesothelial cyst.
Conclusion: Mesothelial cysts occur most frequently in the peritoneal cavity of reproductive-aged women and are often accompanied by endometriosis. Endometriosis is often associated with pelvic peritoneal defects. This report suggests that a mesothelial cyst may extend into the lower abdominal extraperitoneal space through a peritoneal defect caused by endometriosis.