Robot-assisted laparoscopic low anterior resection for rectal cancer with persistent descending mesocolon: A case report

Introduction: Persistent descending mesocolon (PDM) is a fixed abnormality in which the descending to sigmoid colon adheres to the small intestinal mesentery or right pelvic wall through right displacement. Surgery for colorectal cancer with PDM is difficult. Therefore, in addition to the anatomical characteristics of PDM, the extent of adhesion and characteristics of vascular courses need to be assessed in individual patients. The number of patients now undergoing laparoscopic or robot-assisted surgery for colorectal cancer has rapidly increased. We herein report a rectal cancer patient with PDM who safely underwent robot-assisted laparoscopic low anterior resection (RLAR). Presentation of case: A 71-year-old male was referred to our hospital for a detailed examination following a fecal occult blood-positive reaction. Lower gastrointestinal endoscopy revealed a type 2 lesion of the rectum. Moderately differentiated adenocarcinoma was diagnosed based on the results of a histopathological examination. Preoperative contrast-enhanced thoracoabdominal computed tomography showed abnormalities in the colonic course and characteristic vascular courses, suggesting rectal cancer with PDM. RLAR was performed. Discussion: In surgery, it is important to initially perform adhesiolysis accurately in order to reconstruct the original shape of the colonic mesentery and confirm/dissect vascular bifurcations due to the risk of marginal arterial injury. Conclusion: In the present case, a detailed anatomical understanding of the site of intestinal adhesion and vascular courses, as well as surgical procedures, facilitated safe RLAR. We described this case and reviewed the anatomical characteristics of PDM and cautions for surgery.