Gastric heterotopic pancreas can be identified by endoscopic direct imaging with submucosal endoscopy

Heterotopic pancreas (HP) is pancreatic tissue found outside the usual anatomical location of the pancreas, typically in the upper gastrointestinal tract. Asymptomatic HP is considered a benign submucosal tumor (SMT) that can be followed without intervention. However, invasive surgery or endoscopic resection is often inappropriately applied in cases of HP due to the difficulty of preoperative diagnosis by endoscopic ultrasonography (EUS) and tissue sampling error. Therefore, it is very important to distinguish HP from neoplastic SMTs, such as gastrointestinal stromal tumor (GIST), preoperatively. Herein, we describe two asymptomatic gastric HP cases that were distinguished by endoscopic direct imaging (EDI) on submucosal endoscopy with a mucosal flap method (SEMF). In the two patients, EUS-guided fine needle aspiration (FNA) biopsy failed to accurately diagnose two SMTs, consistent with the suspicion of a GIST on EUS. Accordingly, we attempted to perform bloc biopsy using SEMF as a novel method for obtaining tissue samples for two indefinite SMTs. Direct endoscopic imaging via a dissected submucosal tunnel revealed a yellowish, multi-nodular mass identified as pancreatic tissue. Histopathology of the bloc biopsy confirmed the diagnosis of HP. Our findings indicate that the characteristic EDI findings of gastric HP may distinguish these lesions from neoplastic SMTs. Additional evaluations of this approach are warranted.