Submerging endoscopic submucosal dissection leads to successful en bloc resection of colonic laterally spreading tumor with submucosal fat.

A 72-year-old female with a colonic laterally spreading tumor (LST) was referred to our department. A total colonoscopy revealed a large nongranular LST, 30 mm in diameter, in the ascending colon. Detailed examination with chromoendoscopy confirmed that the lesion was an intramucosal tumor, and endoscopic submucosal dissection (ESD) was performed. After a circumferential incision around the lifted lesion with a submucosal fluid cushion, diffuse adipose tissue was observed in the submucosal layer beneath the lesion. The endoscopic view was blurred when dissecting the submucosal layer due to fat adhering to the lens. Since this made it difficult to continue the procedures, we infused water into the lumen and kept the endoscope tip immersed in the collected water. The resulting improved view made it possible to complete all procedures without withdrawing the endoscope to wipe the lens. The lesion was successfully resected en bloc without complications. The pathological examination indicated the curative resection of a tubulovillous adenoma. We propose that a submerged ESD could also be an effective procedure for colonic neoplasms with submucosal fat by avoiding blurring of the endoscopic view.