Uterine fibroids or leiomyomas are the most common benign female genital tumors, although this pathology can also manifest itself outside the uterus, as in the case we present, with a retroperitoneal development. In this article, authors showed a rare case of 81-year-old women, with a right pelvic mass and lower abdominal discomfort. Basing on a preoperative radiological imaging, clinicians oriented to a provisional diagnosis of mesenchymal neoplasm of an uncertain origin. During surgery in the retroperitoneal space, it was detected a huge mass close to the uterus, beneath the right broad ligament. After the opening of the retroperitoneal spaces, surgeons enucleated a well-demarcated tumor, measuring 12 x 7 cm in diameter and histopathological findings demonstrated a rare retroperitoneal uterine leiomyoma.
