In general, perforation of the esophagus is a rare event during endoscopic submucosal dissection (ESD). However, perforation of the esophagus can lead to mediastinitis, which can have a serious outcome. We experienced a perforation due to a partial muscle layer defect during esophageal ESD. We interrupted the ESD and promptly performed appropriate treatment, which may have avoided a serious complication. A muscular layer defect was identified in the subsequent surgical specimen. Since it is difficult to predict a muscular defect before treatment by ESD begins, it is important to make appropriate decisions when a perforation is encountered during esophageal ESD.
