Müllerian and Wolffian ducts originate from the mesodermal tissue. In females, the Müllerian ducts develop to form the fallopian tubes, uterus, cervix, and upper two-thirds of the vagina; whereas in males, they regress. The Wolffian duct, also called the mesonephric duct, regresses in females during development. Mesonephric carcinomas occur through the female genital tract, and the majority arise in the cervix of the uterus. We report the case of a patient who had abdominal pain 4 weeks prior to admission, and who underwent a hysterectomy 20 years prior. The radiologic results revealed a 6.7 × 5.4 × 4.3 cm-sized mass in the retroperitoneum but were not indicative of mesonephric adenocarcinoma. The patient underwent complete mass surgical resection, followed by posterior sectionectomy of the liver and splenectomy with cholecystectomy. The histopathologic results showed that the mass was a mesonephric adenocarcinoma.