Simultaneous Examination of Eosinophil Infiltration in Esophageal Mucosa and Muscle in Patients with Achalasia: Direct Biopsy of the Esophageal Muscle at Per-oral Endoscopic Myotomy.

Submucosal tunneling during POEM provides a safe access for direct esophageal muscle biopsy. This is the first report of the simultaneous biopsy of the esophageal mucosa and muscle in patients with achalasia. Contrary to all previously published studies, the association of esophageal eosinophilic infiltration and achalasia was not observed in this small sample study. Based on our findings, immune or autoimmune reaction rather than direct eosinophilic infiltration in the muscle is more likely the cause of achalasia.