Laparoscopic Sigmoidectomy for Sigmoid Cancer With Persistent Descending Mesocolon: Anatomical Characteristics and Technical Tips

Although rare, persistent descending mesocolon (PDM) is an anatomical anomaly that carries potential risks for laparoscopic colorectal surgery. Impaired blood circulation of the reconstructed colon is especially risky during surgery. We report a case of sigmoid cancer with PDM, in which the patient underwent laparoscopic sigmoidectomy. A 52-year-old man diagnosed with sigmoid cancer was referred to our hospital. PDM was identified with preoperative enhanced-contrast computed tomography, which revealed the sigmoid colon located in the right lower quadrant and a bear-claw inferior mesenteric artery (IMA). Preoperative examination showed cT1N0M0 stage I (Union for International Cancer Control {UICC} eighth). We were not able to identify the branches of IMA after the medial-to-lateral approach. We divided the mesentery and marginal artery and the main branches from IMA extracorporeally prior to lymphadenectomy. Each oral and anal side was dissected without touching the tumor. Then, we marked the line for lymphadenectomy using the dissected line of mesentery as an intracorporeal landmark. Pathological findings showed pT1N0M0 stage I (UICC eighth edition). The patient was discharged without complications. Using this approach and the preoperative recognition of PDM, we performed laparoscopic sigmoidectomy with lymphadenectomy for early-stage PDM case successfully and safely. Our mesocolon dissection-first approach could be a feasible and safer approach for early-stage sigmoid cancer.