[Laparoscopic resection of a retroperitoneal müllerian cyst: a case report]

A 51-year-old woman had a cystic mass in the retroperitoneal space, below the left kidney, which was incidentally detected at a medical check-up. The size of the mass was 6 cm in diameter, which was similar to that obtained by magnetic resonance imaging 4 years ago. We followed the case and found that the mass was slightly enlarged a year later. Because malignancy could not be ruled out, we performed a laparoscopic tumor excision. Histologically, the cyst was diagnosed as a Müllerian cyst, and there was no evidence of malignancy. Retroperitoneal Müllerian cyst is a rare tumor. Sixteen cases have been reported previously and this is the fourth case of a laparoscopic excision.