Use of tunnel endoscopy for diagnosis of obscure submucosal esophageal adenocarcinoma: A case report and review of the literature with emphasis on causes of esophageal stenosis

Figure 2 Upper gastrointestinal endoscopy and endoscopic ultrasonography of the patient. A-D: Upper gastrointestinal endoscopy revealed esophageal stenosis 37 cm from the incisors, along with mucosal surface asperities; E and F: Endoscopic ultrasonography revealed that the esophageal ring cavity was in the stenosis and the muscularis propria markedly thickened, together with an unclear structure of the first to third layers.