Cotyledonoid dissecting leiomyoma of the uterus: a case report of a benign uterine tumor with sarcomalike gross appearance and review of literature.

Cotyledonoid dissecting leiomyoma (Sternberg tumor) is a very rare variant of uterine smooth muscle tumor with an unusual and alarming gross appearance. Including our case, approximately 20 cases were reported in the literature. A 27-year-old woman presented with pelvic mass. A 41-cm fungating rubbery mass with placenta-like appearance adhering to the posterior uterine surface and extending to the left broad ligament and pelvic cavity was observed. An intraoperative frozen section was requested, and a diagnosis of a benign smooth muscle tumor was given. Total abdominal hysterectomy and bilateral salpingo-oophorectomy were performed with removal of the pelvic tumor extension. Thorough tumor sampling was performed and showed nodules of interlacing bundles of bland-looking smooth muscle cells, separated by expanded, edematous, and highly vascularized stroma. No atypia, mitotic activity, or coagulative necrosis was seen. Immunohistochemical studies confirmed the smooth muscle nature of the tumor. Cotyledonoid leiomyoma has a distinctive gross appearance which usually raises the suspicion of sarcoma. Intraoperative frozen section is a mandatory and helpful procedure to avoid overtreatment of such cases.