Carcinoma located in a right-sided sigmoid colon: A case report.

Background: A right-sided sigmoid colon is an extremely rare anatomic variation that should be considered as a possibility by surgeons and radiologists before surgery. Here, we report the first clinical case of a carcinoma in a right-sided sigmoid colon revealed by a preoperative computed tomography (CT).

Case Summary: A 56-year-old Chinese man was admitted to the hospital with abdominal pain. CT revealed a redundant sigmoid colon with a mass on the right side of the cecum and ascending colon. Laparoscopy confirmed an abnormal course in the descending colon and sigmoid colon. Subsequently, hemicolectomy was performed in an open manner after laparoscopic exploration. Pathological examination revealed an infiltrative mucinous adenocarcinoma with two lymph node metastases. The patient was discharged without any complications after a week. There were no signs of recurrence or metastasis during the 3-month follow-up period.

Conclusion: We report a rare anomaly of a right-sided sigmoid colon with carcinoma, which should be differentiated from ascending colon cancer and pericecal hernia to prevent errors and other surgical complications.