Abstract
BACKGROUND: Intestinal malrotation is a condition in which the process of counterclockwise rotation and fixation to the peritoneum and retroperitoneum during fetal life is incomplete. In adults, it is generally asymptomatic and is often discovered incidentally. We report a case of laparoscopic partial resection of the descending colon for a tumor of the descending colon with a rare form of intestinal malrotation in which the inferior mesenteric artery ran symmetrically and the sigmoid colon was fixed to the dorsal cecum and right-sided retroperitoneum. CASE PRESENTATION: A 75-year-old man was referred to our department of internal medicine due to a positive fecal occult blood test. Lower endoscopy revealed a laterally spreading tumor in the descending colon, and endoscopic submucosal dissection was attempted; however, this procedure was difficult, and the patient was referred to our department for surgical treatment. Contrast-enhanced computed tomography revealed that the endoscopic clip was located in the descending colon on the right side, the inferior mesenteric artery was symmetrical, and the sigmoid colon was located on both the right and dorsal sides of the cecum. Laparoscopic ileocecum and sigmoid colon mobilization was performed from the left side of the patient. After the completion of sigmoid colon mobilization, which returned the sigmoid colon and descending colon to anatomical normalcy, laparoscopic partial resection of the descending colon was performed. Based on the results of a histopathological examination, a granular type of laterally spreading tumor was diagnosed. The patient was discharged uneventfully on postoperative day 8. CONCLUSIONS: Detailed preoperative imaging and surgical simulation are necessary for abdominal surgery involving intestinal malrotation.