Supplementary Material for: Underwater endoscopic mucosal resection for a terminal ileum adenoma

Tumors of the terminal ileum are rare, and their diagnosis and treatment standards have not been established. The effectiveness of underwater endoscopic mucosal resection (UEMR) in the duodenum and colon has been reported; however, its effectiveness in the small intestine is rarely reported. We present a case of an ileum adenoma diagnosed using magnifying endoscopy that was completely resected using UEMR. A 56-year-old woman with a lesion in the terminal ileum was referred to our hospital for treatment. Colonoscopy revealed a 10- mm slightly depressed lesion with marginal elevation in the terminal ileum. Magnifying narrow-band imaging (NBI) showed a tubular surface pattern with regular vessels on the slightly elevated marginal area and regular brown vessels on the slightly depressed central area. Magnifying chromoendoscopy using crystal violet staining showed a branch-like or gyrus-like pattern on the marginal area, and a roundish and tubular structure on the central area. The lesion was diagnosed as an adenoma in the terminal ileum, similar to a colonic adenoma; hence, we decided to perform UEMR. The lesion was completely removed using a 10- mm snare. The pathological diagnosis revealed that it was an intestinal-type adenoma with negative margins. At the margins of the lesions, the tumor tended to form a villous structure, while the center appeared tubular with a relatively flat surface. These histopathological findings were consistent with the magnifying endoscopic findings. UEMR for terminal ileum tumors may be effective in their treatment.