Degenerated huge retroperitoneal leiomyoma presenting with sonographic features mimicking a large uterine leiomyoma in an infertile woman with a history of myomectomy: a case report

INTRODUCTION: Retroperitoneal leiomyomata are rare. They are either mistaken preoperatively for malignant retroperitoneal tumors or dealt with as cases of subserous leiomyomata that turn out intraoperatively to be huge retroperitoneal masses of unknown nature. CASE PRESENTATION: We report the case of a 46-year-old nulligravid female patient of Middle Eastern ethnicity who presented to our university hospital with lower abdominal as well as pelvic pain along with a bloated sensation. She also reported noticing an unusual increase in her abdominal girth. These symptoms developed over the previous two months. Preoperative investigation by means of an ultrasound suggested a degenerated subserous huge uterine leiomyoma. An abdominal hysterectomy was planned. Intraoperatively, a normal sized uterus was found, the surface of which was studded with multiple variable sized pedunculated subserous leiomyomata. Another huge retroperitoneal soft to firm mass was found extending from her left pelvic wall to the level of her spleen, with no connections to her uterus. The mass was excised and a histopathological examination revealed a degenerated leiomyoma. CONCLUSION: Some unusually located extra-uterine leiomyomata have been reported; retroperitoneal leiomyoma being among them. The origin of such tumors is still obscure; a parasitic origin as well as Müllerian cell rests or smooth muscle cells in the retroperitoneal vessels wall have been suggested. An 'iatrogenic' origin for such growths is also a possible theory. The origin of uncommonly located leiomyomata is an unexplored issue that merits more investigation.