Mesenteric lymph node recurrence at six years after endoscopic resection for a submucosal sigmoid colon cancer

A 60-year-old woman admitted for high serum carcinoembryonic antigen (CEA) and a mass 3.7cm in diameter in the left pelvic cavity detected by FDG-PET/CT had undergone endoscopic resection six years earlier for a type 0-Ip sigmoid colon polyp 15mm in diameter pathologically diagnosed as well-differentiated adenocarcinoma with submucosal and lymphatic invasion. Sigmoidectomy with lymph node dissection was not done then due to negative tumor cell margin. Based on her history, preoperative diagnostic imaging, and intraoperative findings, we diagnosed the left pelvic mass as mesenteric lymph node metastasis originating in endoscopically resected sigmoid colon cancer. We then conducted sigmoidectomy with lymph node dissection (D3) resulting in pR0 resection. Because the metastatic lymph node exposed the peritoneal surface of the mesenterium, cytology of a small amount of intrapelvic ascites resulted in a Class IIIb diagnosis. The risk of peritoneal dissemination was considered. In endoscopically resected cases of submucosal invasive colorectal cancer with lymphatic invasion and negative tumor cell margins, we should thus select additional surgery or implement surveillance to detect recurrence at an early stage.