Pneumothorax following endoscopic submucosal dissection of a rectal tumor

Endoscopic submucosal dissection is a useful alternative to endoscopic mucosal resection and surgery for en bloc resection of colorectal tumors. However, the technique is considered to be difficult, and potential complications include perforation and postoperative bleeding. In this case report, we present a case of a 63-year-old woman who developed pneumothorax after endoscopic submucosal dissection of a rectal tumor.