Abstract
An 18-year-old man presented with pains from the epigastric region to the lower right abdomen. An abdominal contrast enhanced computed tomography revealed a huge tumor measuring 150 × 70 mm extending from the right lower quadrant of abdomen to the pelvic cavity that obtained blood flow from the superior mesenteric artery. We suspected the tumor to have derived from the ileocecal intestine or mesentery and performed surgery for the purpose of diagnostic treatment. Upon laparotomy, there was a moderate degree of bloody ascites. The tumor firmly adhered to the peritoneum, the bladder, and the ileum of approximately 30 cm in length, and it was removed by combined resection with the ileum. His postoperative course was uneventful and he was discharged on 8th postoperative day. Histopathologically the tumor was diagnosed as Ewing's sarcoma/peripheral primitive neuroectodermal tumor (ES/pPNET) derived from the ileal mesentery. Although the tumor itself could be resected, intraoperative ascites cytology found tumor cells ; thus, the patient was referred to a higher-level medical institution to receive adjuvant chemotherapy in consideration of possible intra-abdominal micrometastasis. Fifteen months after the operation, the patient has not experienced any macroscopic recurrence. Here we report a case of ES/pPNET originating from the mesentery, because it is a very rare disease.
