Tubular Adenoma With High-Grade Intraepithelial Neoplasia Arising From Heterotopic Gastric Mucosa in the Cervical Esophagus

ABSTRACT Heterotopic gastric mucosa of the cervical esophagus, while common, rarely undergoes neoplastic transformation. We report a rare case of a 55-year-old man with a 0.8 cm sessile elevated lesion (Paris 0-Is) arising within a cervical inlet patch. Meticulous endoscopic evaluation using magnifying narrow-band imaging and endoscopic ultrasound identified features suggestive of neoplasia, including irregular microvascular and microsurface patterns. Despite technical challenges due to the narrow cervical lumen and external compression from the endotracheal tube cuff, endoscopic submucosal dissection was successfully performed. Histopathology confirmed a tubular adenoma with high-grade intraepithelial neoplasia exhibiting an intestinal phenotype (MUC2+, CD10 + ). This case emphasizes the importance of careful screening of the esophageal blind spot and the efficacy of endoscopic submucosal dissection as a curative treatment of early-stage neoplasia in this challenging location.