[A case of retroperitoneal Mullerian cyst resected laparoscopically].

A 67-year-old female patient had a cystic mass, 6 cm in diameter, which was incidentally detected on the dorsal side of the cecum in the retroperitoneum. A laparoscopic tumor excision was performed. Microscopically, the majority of the cystic wall consisted of Mullerian type serous epithelium, partially including the columnar epithelium containing round nuclei and mucin production. The columnar epithelium was similar to the uterocervical epithelium, and there was proliferation of dense collagen fibers resembling ovarian stroma under the epithelium. These microscopic findings were consistent with ovarian seromucinous cystadenoma. Therefore, the cyst was diagnosed to be a retroperitoneal Mullerian cyst. This is the 15th case of a cyst of this type reported and is the first case in which a laparoscopic excision was performed.