Muscle resection biopsy during peroral endoscopic myotomy in a patient with achalasia

Esophageal achalasia is an esophageal motility disorder, primarily characterized by degeneration of the esophageal myenteric plexus.¹ Although the myenteric plexus is the primary concern during pathogenesis of achalasia,² a method for endoscopically sampling it has not yet been established. We report a novel sampling method—muscle resection biopsy—designed to sample the myenteric plexus while distinguishing between the circular and longitudinal muscle layers during peroral endoscopic myotomy (Video S1). A submucosal tunnel was first created and a small full-thickness muscle incision was made just above the lower esophageal sphincter using a needle-type knife (FlushKnife BTS3.0; FUJIFILM Holdings Corporation, Tokyo, Japan) and laterally extended to both sides, forming a U shape (Fig. 1a). A hemostatic clip (EZclip; Olympus Corporation, Tokyo, Japan), with one arm marked in red, was applied to the shaped muscle layers with the marked arm on the luminal side (Fig. 1b,c). We then excised the remaining muscle layers using a snare (SD-221L-25; Olympus Corporation; Fig. 1d) and collected the resected tissue.

Peroral endoscopic muscle biopsy using a submucosal tunnel has been recognized as a simple and useful sampling method for evaluating eosinophilic infiltration and fibrosis in the muscle layer.³ However, the small size of biopsy samples and tissue damage caused by biopsy forceps make identifying the myenteric plexus and preserving the structures of both the circular and longitudinal muscle layers challenging. Although this method is time-consuming, requires skillful manipulation of an endoknife, and has potential risk of bleeding, it enables the collection of large, undamaged, tissues via biopsy forceps and allows for identification of the myenteric plexus and muscle layers while preserving the microscopic structure of the luminal wall (Fig. 2). Histopathological information obtained by this approach can be useful for assessing the microenvironment underlying the neurodegeneration in combination with immunohistochemical staining results.

Authors declare no conflict of interest for this article.