Intra-abdominal ovarian-type mucinous cystadenoma associated with fallopian tube-like structure and aberrant epididymal tissue in a male patient.

Ovarian-type mucinous tumors may occasionally occur in the retroperitoneum, pancreas, and liver exclusively or almost exclusively in women. In men, only few cases of such neoplasms arising within or around the testis have been reported. We describe a unique case of an ovarian-type mucinous cystadenoma occurring in the peritoneal cavity of a 65-year-old male patient with secondary adrenocortical insufficiency and hypogonadism. There was a typical fallopian tube enclosed in the capsule of the tumor. Contiguous to that, accessory ectopic epididymal tissue was found. We have interpreted this case as the result of a minor disorder of embryonic development involving structures of both müllerian and wolffian origin. The disproportion of sexual hormones might have had a role in inducing intra-abdominal müllerian remnants to give rise to the mucinous cystadenoma.