RESUMO
In the literature, 51 cases of primary retroperitoneal mucinous cystadenocarcinoma have been published. We report the fourth case occurring in a male patient. The 42-year-old patient presented with multiple retroperitoneal cystic masses causing abdominal discomfort without alteration of the global clinical state. The masses were totally removed by a two-stage surgery. No other treatment has been introduced. After a follow-up of 6 months, the patient is disease-free. This rare tumor most likely arises from the mucinous metaplasia of peritoneal inclusion cysts rather than from ectopic ovarian tissue or ovarian teratomas. The occurrence of such a tumor in a male patient supports this theory. Preoperative diagnosis is mostly difficult. Clinical behavior and treatment are still controversial.