Underwater endoscopic mucosal resection for neoplasms in the pyloric ring of the stomach: Four case reports

BACKGROUND: Tumors located in the pylorus are technically more complex to resect by endoscopic resection, as the anatomical characteristics of this region can affect the adequate assessment of margins and performance of the procedure. We reported the results of underwater endoscopic mucosal resection (UEMR) of benign mucosal neoplasms located in the pyloric ring. CASE SUMMARY: This case series describes 4 patients with 4 mucosal neoplasms located in the pyloric ring. The diameter of each neoplasm was less than 15 mm. We performed UEMR for the lesions. Water immersion enabled slight floating of the lesions, resulting in easy identification. We achieved en bloc resection with a snare and electrosurgical unit. All procedure were performed within 3 min without adverse events. Pathologic examination showed low-grade dysplasia with clear resection margins in one case and hyperplastic polyps in three cases. CONCLUSION: UEMR can be an effective and safe treatment method for neoplasms in the gastric pyloric ring.