LAUSR

A 68-year-old man was referred to our hospital for endoscopic treatment of a nongranular pseudodepressed laterally spreading tumor (LST) of the hepatic flexure with a histological diagnosis of adenocarcinoma discovered in another center and for which he refused surgery. At the endoscopic examination, using blue light imaging and linked color imaging (Fujifilm, Valhalla, New York, USA), we observed a nongranular LSTwith features suggestive of deep submucosal invasion (central depression and Vi pattern according to Kudo classification) (▶Fig. 1). An underwater endoscopic submucosal dissection was performed (▶Video 1). The procedure was carried out using a T-type HybridKnife (Erbe, Tübingen, Germany). To start, an incision was made on the anal side; then the colon was filled with saline, and an underwater submucosal pocket was created under the lesion (▶Fig. 2). Finally, the circumferential incision was complete and the tumor was removed en bloc. In the end, the muscular layer was clear, without any defects or exposed vessels (▶Fig. 3). The procedure was completed without any adverse events and the patient was discharged the day after. The resected specimen (▶Fig. 4) showed an adenocarcinoma arising in a tubulovillous adenoma, 35×30mm in size, with poorly differentiated clusters, infiltration of the submucosa layer (2200 microns), clear margins, aspects of lymphovascular invasion, and low-grade budding. To check for high-risk features of metastatic disease, an abdominal computed tomography was performed and did not show any metastasis. The patient was resent to surgery, which he again refused. Our case shows that underwater submucosal dissection is safe and effective for complete resection of colic neoplasia [1, 2] even when the submucosal layer is involved.