Mullerian cyst of the uterus misdiagnosed as ovarian cyst on pelvic sonography.

Mullerian cyst of the uterus, also known as endosalpingiosis, is rare and often can be misdiagnosed as adnexal cyst on pelvic sonography. A 47-year-old woman was referred for an incidental finding of a right adnexal mass on pelvic sonography, suspected to be an ovarian cyst. During laparoscopy, a pedunculated cystic mass arising from the right anterior uterine wall was seen. The mass was resected laparoscopically and histologic examination showed a benign Mullerian cyst of the uterus. Diagnosis of Mullerian cyst of the uterus can be challenging. However, with increased awareness, preoperative diagnosis of this condition should be possible sonographically.