[Spontaneous Disappearance of Undifferentiated Pleomorphic Primary Mesenteric Sarcoma-A Case Report].

The patient was a 49-year-old man with persistent fever since the introduction of hemodialysis(HD). Vomiting and abdominal swelling appeared 4 months after initiating hemodialysis. Computed tomography(CT)scan revealed a tumor measuring 9 cm, and disorders of passage from the jejunum. Surgery was performed, and resection was impossible because of peritoneal dissemination. Histopathological examination of the disseminated nodes suggested an undifferentiated pleomorphic sarcoma. Postoperatively, drainage from the gastric fistula was approximately 2,000mL/day. Chemotherapy was considered impossible because of HD, and palliative therapy was selected. However, the volume of drainage from the gastric fistula gradually decreased, and the disorders of passage reduced. CT scan confirmed marked reduction in the size of the intraperitoneal tumor and its subsequent disappearance. At the 2-year-and-5-month postoperative follow-up, no relapses were observed, and the course had been uneventful. Undifferentiated pleomorphic sarcomas develop in the soft tissue of adults and have a poor prognosis. However, mesenteric development is rare. Total tumorectomy is the first choice of treatment. A consensus on the usefulness of chemotherapy or radiotherapy has not been reached. Furthermore, no studies have reported spontaneous tumor disappearance in the absence of treatment. Here, we report a case of minor undifferentiated primary mesenteric sarcoma and its spontaneous disappearance and review the literature.