Synchronous gastric-type intraepithelial neoplasia and ectopic pancreas in the gastric antrum diagnosed by en bloc endoscopic submucosal dissection: a case report and literature review

Abstract

Ectopic pancreas is a relatively common submucosal lesion of the stomach and is generally considered benign. Emerging evidence, however, suggests that ectopic pancreas may coexist with synchronous neoplastic changes of the overlying gastric mucosa. Because submucosal protrusions can obscure subtle surface abnormalities during endoscopic examination, such coexistence may increase the risk of missed diagnosis. A 53-year-old woman presented with intermittent epigastric discomfort for more than 1 year. Upper gastrointestinal endoscopy (gastroscopy) revealed a persistent lesion on the greater curvature of the gastric antrum, characterized by an irregular mucosal elevation with central depression and erosion. Magnifying endoscopy with narrow-band imaging demonstrated irregular microvascular architecture within the lesion, and targeted multi-site biopsies were obtained. Histopathology suggested gastric epithelial dysplasia; preoperative pathology and immunohistochemistry indicated indefinite neoplasia for glandular epithelium, and endoscopic submucosal dissection was recommended. The patient underwent endoscopic submucosal dissection. During the procedure, a whitish submucosal nodule was identified and removed en bloc together with the mucosal lesion. Postoperative histopathology demonstrated gastric-type intraepithelial neoplasia (focal high-grade dysplasia) coexisting with ectopic pancreatic tissue (acini and ducts). The two components were histologically independent without evidence of direct continuity. No postoperative complications occurred. This case highlights that gastric-type intraepithelial neoplasia (focal high-grade dysplasia) can coexist with ectopic pancreas within the same antral region while remaining histologically separate. For suspected ectopic pancreas or other submucosal protruding lesions in the gastric antrum, careful and systematic assessment of the overlying mucosa with targeted biopsies is important to avoid overlooking superficial neoplastic lesions masked by submucosal elevation. Endoscopic submucosal dissection can provide a definitive pathological diagnosis and enable en bloc resection of coexisting mucosal and submucosal components in selected cases.