A 73‐Year‐Old Man With Intermittent Dysphagia and Esophageal Wall Thickening: What Is the Diagnosis?

This case report describes a 73‐year‐old man with more than 1 year of intermittent dysphagia, initially suspected of having esophageal malignancy based on imaging and endoscopic findings. However, multiple mucosal biopsies revealed only mild dysplasia without eosinophilic infiltration. Endoscopic ultrasound performed at our hospital revealed a preserved four‐layer esophageal wall structure with diffuse thickening of the muscularis propria at 30–40 cm from the incisors. Definitive diagnosis was ultimately achieved through peroral endoscopic myotomy (POEM) combined with biopsy, which revealed marked eosinophilic infiltration confined to the muscularis propria, consistent with eosinophilic esophageal myositis. POEM provided both diagnostic and therapeutic benefits, leading to substantial clinical improvement and weight gain over 1 year of follow‐up without the use of corticosteroids.