Single-channel transcolonic endoscopic appendectomy for a sessile serrated lesion with dysplasia of the appendiceal stump.

A 53-year-old woman with a history of laparoscopic appendectomy for acute appendicitis 20 years ago presented to our endoscopy center for colonoscopy surveillance and found a circumferential Paris 0-IIb laterally spreading lesion in the appendix orifice. After indigo carmine mixed saline staining, the lesion showed a type II-open pit pattern, which grew into the appendiceal residual lumen. The single-channel transcolonic endoscopic appendectomy (TEA) was performed. The histopathologic analysis confirmed a sessile serrated lesion (SSL), and serrated morphology was observed in multiple crypts, with mild nuclear atypia. The patient experienced no complications during hospitalization, and a follow-up colonoscopy four months post-procedure revealed satisfactory healing of the defect.