A case of pure neurinoma of the retroperitoneal space developing in the pelvis is described. This tumor (phi max, 15 cm) responsible for intense compressive symptomatology involving the pelvic organs, was at first mistaken for a uterine fibroid. The ultimate diagnosis both of neurinoma as well as every other neoplasm originating in the retroperitoneum can sometimes be very hard to obtain. Those tumors can indeed be misdiagnosed for other more common conditions both clinically and instrumentally and the rarity of this particular localization adds further trouble to the matter.