Retroperitoneal leiomyosarcoma: a case report.

: Retroperitoneal leiomyosarcoma is a relatively rare and aggressive tumor. Because of its rarity, it is difficult to arrive at a definite diagnosis preoperatively and to design an effective strategy. Here the authors report a case of peritoneal leiomyosarcoma in which diagnosis was difficult because the clinical course resembled that of ovarian cancer. A 77-year-old woman diagnosed with ovarian cancer underwent laparotomy. The excised tumor contained a necrotic polypoid mass that histologically displayed the features of leiomyosarcoma. The patient received adjuvant chemotherapy with a combination of gemcitabine and docetaxel but died two months after surgery owing to the aggressive behavior of the tumor. Because the preoperative diagnosis in this case was ovarian cancer, arriving at a treatment strategy assuming peritoneal leiomyosarcoma was difficult. If complete surgical resection of tumor is not performed, as in the present case, the prognosis can be extremely poor.