Peranal endoscopic myectomy (PAEM) for rectal lesions with severe fibrosis and exhibiting the muscle-retracting sign

Background  Although endoscopic submucosal dissection has enabled complete tumor resection and accurate pathological assessment in a manner that is less invasive than surgery, the complete resection of lesions with severe fibrosis in the submucosal layer and exhibiting the muscle-retracting sign is often difficult. We have devised a new method, peranal endoscopic myectomy (PAEM), for rectal lesions with severe fibrosis, in which dissection is performed between the inner circular and outer longitudinal muscles, and have examined the usefulness and safety of this new technique. Methods  All of the patients who underwent PAEM in our hospital and affiliated hospitals between July 2015 and June 2017 were retrospectively reviewed. Results  10 rectal lesions were treated with PAEM. En bloc resection with a negative vertical margin was achieved in eight patients (80 %), whose lesions were mucosal (n = 2), shallow submucosal (n = 1), deep submucosal (n = 4), and muscle invasive (n = 1). The clinical course of all patients after PAEM was favorable. In patients who underwent additional surgery, anus preservation was achieved on the basis of the pathological results from PAEM. Conclusions  PAEM for lesions with severe fibrosis exhibiting the muscle-retracting sign appears to be both safe and useful.