Colonic muco-submucosal elongated polyp: diagnosis with endoscopic ultrasound.

Colonic muco-submucosal elongated polyp is a new clinical entity first reported in 1998. The purpose of this report is to determine the value of endoscopic ultrasound in the diagnosis of this condition. We reviewed the endosonographic and histological findings of seven colonic muco-submucosal elongated polyps that were removed completely by endoscopic resection or surgery. The lesions appeared as pedunculated submucosal tumours, measuring 1-4 cm in maximal diameter. Endosonographically, all lesions consisted of mucosal and submucosal layers, and microcystic components were found in the submucosal layer. There were no echogenic masses or muscularis propria within the polyps. These endosonographic features corresponded to histological findings of this type of polyp which was covered with normal mucosa and composed of submucosal layer alone. The submucosal layer consisted of oedematous, loose, connective tissue and/or fibrous tissue, accompanied by dilated blood vessels and lymphatics. Endoscopic ultrasound enabled differentiation of colonic muco-submucosal elongated polyp from other submucosal lesions.