Laparoscopic right hemicolectomy for ascending colon cancer with persistent mesocolon.

Persistent ascending or descending mesocolon is an embryological anomaly that occurs during the final process of intestinal development in organogenesis. Specifically, the primitive dorsal mesocolon fails to fuse with the parietal peritoneum in the fifth month of gestation. Herein, we describe a case of ascending colon cancer with persistent ascending and descending mesocolon treated by laparoscopic right hemicolectomy. Preoperative computed tomography imaging of the abdomen demonstrated that the descending colon shifted at the midline of the abdomen and the sigmoid colon was located under the ascending colon. The detailed preoperative imaging examination revealed malpositioning of the large intestine and aided in the procedural planning. Because persistent mesocolon may result in the formation of abnormal adhesions, an accurate preoperative diagnosis is essential. We propose that it is important to consider this anomaly when making the preoperative imaging diagnosis to ensure a safe operation.