Lessons from imperfect endoscopic submucosal dissection of rectal tumor.

Endoscopic mucosal resection (EMR) is a standard endoscopic treatment for gastrointestinal tumors, but resections done in a piecemeal fashion are difficult to diagnose pathologically as curative resections, and the local recurrence rate is relatively high. Recently, endoscopic submucosal dissection (ESD) for colorectal tumors, which provides a higher complete resection rate than conventional EMR, has rapidly come into widespread use in Japan. However, colorectal ESD is still technically difficult and has complications such as perforation, and the procedure time is longer than that of conventional EMR. We report herein a case in which a rectal tumor was resected with an inappropriate specimen due to imperfect ESD. This lesion had severe fibrosis in the submucosal layer because the lesion had been injected with a solution for EMR in another hospital, which resulted in non-lifting signs, and had been subjected to many biopsies. During the ESD in our hospital, the submucosal layer was not clearly identified, and a small injury was caused in the specimen. A precise diagnosis based on histopathological findings could not be made because of the inappropriate specimen. Thus, expertise in both the diagnostic and the therapeutic aspects is required before treating large colorectal tumors.