Successful Endoscopic Excision for a Rapidly Enlarging Esophageal Histopathologically Unclassified Subepithelial Lesion: A Case Report

A 75‐year‐old man presented with an esophageal subepithelial lesion (SEL) measuring 2.5 cm, first identified over a decade ago. The patient was followed up regularly with computed tomography and endoscopy and remained asymptomatic since then. However, over the past year, the patient developed dysphagia, and endoscopic evaluation revealed that the tumor had enlarged to 6.0 cm. Although nine endoscopic examinations with biopsies were performed, no definitive histopathological diagnosis was established. Endoscopic ultrasonography revealed that the tumor originated primarily from the submucosa. Given the rapid growth of tumor size and progressive symptoms, the tumor was removed with endoscopic submucosal dissection (ESD) in an en bloc manner. Histopathological analysis revealed a SEL characterized by vascular proliferation, thickening of the lamina muscularis mucosa, and inflammatory changes. No evidence of neoplasm was identified, suggesting the presence of a reactive lesion. The patient's dysphagia improved following ESD, and no recurrence was observed during a 15‐month follow‐up period. To date, no reports have documented rapidly growing esophageal SELs with abundant vascularization during follow‐up.