Premalignant lesion of heterotopic pancreas combined with gastritis cystica profunda in gastric fundus.

Heterotopic pancreas, also known as ectopic pancreas, is found mainly in the stomach, duodenum, or jejunum. Pancreatic intraepithelial neoplasia (PanIN) is the non-invasive precursor of pancreatic cancer and gastritis cystica profunda (GCP) is considered a precursor of gastric cancer. As with most putative cancer precursor lesions, the diagnosis and treatment of these lesions has been controversial. A patient with no history of gastric surgery visited our institution for a regular evaluation. Endoscopy showed a 2 x 2 cm sized, protruding mass lesion with overlying normal mucosa on the fundus of stomach. Endoscopic ultrasound (EUS) and computed tomography (CT) led to the possible diagnosis of a gastrointestinal stromal tumor with cystic change. Laparoscopic gastric wedge resection was performed with intra-operative endoscopic guidance. Microscopic examination identified the mass as pancreatic tissue. Furthermore, it demonstrated PanIN, grade 3 (PanIN-3) mixed pancreatobiliary and intestinal type, arising in the heterotopic pancreas and associated with GCP. This report describes a rare case of a PanIN lesion combined with GCP as precursors of precancerous lesions in heterotopic pancreas and stomach.