Endoscopic Resection of a Rectal Neuroendocrine Tumor: Hybrid Endoscopic Submucosal Dissection

A 67-year-old man was referred to our institution due to a 10-mm yellowish subepithelial lesion in the middle rectum incidentally diagnosed during screening colonoscopy. Conventional biopsies showed a well-differentiated neuroendocrine tumor (NET). Abdominopelvic computed tomography and endoscopic ultrasound showed limited submucosal invasion and no locoregional/distant metastasis. It was decided to perform a hybrid endoscopic submucosal dissection (ESD) technique. First, submucosal injection was performed using methylene-blue-stained saline containing 1: 100,000 epinephrine with adequate lesion lifting; second, a circumferential incision with a 1–2 mm free margin (ERBE VIO 300D: Endocut I, effect-1) was made using a ClearCut knife 2 mm I-type (Finemedix, South Korea); third, a partial submucosal dissection was done, using the same knife and settings; and fourth, an en bloc resection with an oval 15-mm diathermic snare (Olympus, Spain) was performed (Forced Coag, effect-2 80 W) without complications and resection time of 9 min (Fig. 1a–f). Histopathology showed a 9-mm NET G1 (WHO classification, 0 mitoses/10 HPF, Ki-67: 1.8%; pT1a AJCC stage 1), limited to the submucosa with free lateral (1.0 mm) and deep (0.6 mm) resection margins (Fig. 2a–g). Considering R0 resection of a < 10-mm rectal NET (R-NET), no followup was scheduled. Despite the increasing incidence due to the widespread use of screening colonoscopy, R-NET are relatively rare and often well differentiated [1–5]. Endoscopic resection plays a central role in the resection of small well-differentiated R-NET (< 10 mm) and selected cases measuring 10–20 mm, given the low risk of metastasis [2–4]. There is no consensus regarding the best endoscopic resection technique [1, 2, 4, 5], including conventional polypectomy, endoscopic mucosal resection (EMR) or ESD. Conventional polypectomy should be avoided as complete resection is often not achieved [1, 4] and EMR shows a suboptimal complete resection rate (30–70%) due to frequent submucosal involvement affecting mostly the vertical margin [1, 3, 5]. Incomplete resection requires endoscop-