Peranal endoscopic myectomy (PAEM) is a novel endoscopic technique for removing lesions together with the inner circular muscle layer in patients with lower rectal tumors with severe submucosal fibrosis [1] [2] [3] [4]. In this procedure, the outer longitudinal muscle is exposed at the resection area and its fragility poses a risk for perforation. As there are few reports on PAEM, the thickness of the muscles in the lower rectum is not well known. In our experience, the outer longitudinal muscle is usually dense and the extraluminal tissue is invisible ([Fig. 1]). Herein, we present the management of a patient with a sparse outer longitudinal muscle layer ([Video 1]).