Anatomical challenge: a case of cecal cancer with intestinal incomplete rotation.

[Background]Intestinal malrotation is a congenital anomaly, mainly diagnosed and treated during childhood. In the present study, we report a case of cecal cancer with intestinal incomplete rotation, revealed during the operation for cecal cancer.[Case presentation]An 81-year-old woman referred to our hospital, claiming about intermittent abdominal pain. Computed tomography showed ileal dilation with stricture on ileo-cecal valve. She emergently admitted and underwent the placement of transnasal ileus tube. After decompression, laparoscopic ileo-cecal resection was performed. During the operation, duodenum was found to be running near the right-dorsal space of superior mesenteric artery, but not passing through. Meanwhile, the cecum placed in the right quadrant of the abdomen. At this moment, we diagnosed intestinal incomplete malrotation. Since the intestinal mesentery all attached to the dorsal side of the proximal colonic mesentery, we carefully resected ileo-cecal vessels and lymph nodes without anatomical misunderstanding. In this procedure, lateral approach was effective, because resecting lateral membranous structure between ascending colon and retroperitoneum like Ladd ligament revealed the duodenum. [Discussion and conclusion]Intestinal malrotation in adulthood is rarely and incidentally revealed during the operation for other disease, sometimes confusing surgeons due to anatomical abnormality. Intraoperative discussion and approach enabled us to complete the laparoscopic surgery with oncological accuracy and safety.