Follow-up of 35 appendiceal orifice neoplasms resected by endoscopic full-thickness resection

Endoscopic full-thickness resection (EFTR) is an established, safe technique for the resection of appendiceal orifice (AO) neoplasms. Post-EFTR appendicitis is a recognized adverse event. There are no systematic reviews, and there is a paucity of literature with assessed outcomes, particularly with respect to delayed appendicitis, mucocele, or fistula formation. We aimed to evaluate the efficacy of EFTR for AO lesions.

Consecutive AO lesions referred for consideration of EFTR were prospectively studied. Multiple data points were recorded including technical success, EFTR histopathologic data, adverse events, and follow-up surveillance data via colonoscopy. Surveillance CT was performed because of concerns of potential mucocele from the obstructed remnant appendix.

Over a 4-year period, starting from July 2019 till July 2023, 37 AO lesions were referred to a tertiary center for consideration of EFTR. EFTR was attempted in 35 (95%) lesions. Most lesions were small (median size 10 mm, interquartile range [IQR] 10-15 mm), exhibiting Paris 0-IIa morphology (n = 32, 91%) with serrated histopathology n = 17, 49%). R0 resection was achieved in most EFTR cases (n = 30/35, 86%). Adverse events included appendicitis (n = 4, 11%) and delayed bleeding (n = 2, 6%). At 6-month (IQR 4-6 months) surveillance colonoscopy, there was 1 (3%) case of residual lesion. This was successfully treated endoscopically, confirmed on a second surveillance colonoscopy. There was 1 case of appendicitis of the remnant at 7 months. At surveillance CT abdomen/pelvis (median 15 months, IQR 7-37 months), 2 of 17 (12%) fistulas were identified. Both of these patients had presumed adhesions due to abdominal surgery before EFTR.

In conclusion, EFTR is an effective technique for the curative resection of select, small (<15 mm) Paris 0-IIa AO lesions. Appendicitis is a relatively common adverse event but is often managed conservatively. The long-term significance of post-EFTR fistulas remains unclear. Caution should be exercised when considering EFTR in a patient with prior regional surgery.