Acute Appendicitis Caused by Previous Endoscopic Submucosal Dissection for an Adenoma Adjacent to the Appendiceal Orifice.

Endoscopic submucosal dissection (ESD) is a groundbreaking treatment for tumors adjacent to the appendiceal orifice that are difficult to remove by conventional endoscopic mucosal resection, and successful cases are increasingly reported. However, little is known about the subsequent complications, especially long-term complications. A female in her early 70s with a 15-mm cecal tumor adjacent to the appendiceal orifice - discovered incidentally during a screening colonoscopy - underwent hybrid ESD of the lesion. We completely resected the tumor, and she was discharged 5 days later with a pathological diagnosis of high-grade tubular adenoma. Ten months postoperatively, she experienced sudden-onset right lower quadrant pain and was diagnosed with acute appendicitis at another hospital. Due to suspicion that her condition was the result of residual tumor, her surgeon performed an emergency laparoscopic cecectomy. The pathological examination of the resected specimen showed thick scarring adjacent to the appendiceal orifice and no residual tumor. The previous ESD was identified as the cause of the scar, and the scar was the only finding to account for the patient's appendicitis. This case is significant because the patient required additional surgery due to a complication of ESD. Further, it indicates that acute appendicitis may be a late complication of submucosal dissection near the appendiceal orifice. As ESD becomes more widely used, it is likely that more cecal tumors will be treated endoscopically. It is important to be aware of the late complications of ESD for these tumors.