Fig. 1Endoscopic findings. (A) A subepithelial tumor with a nodular shape is found at the lesser curvature in the lower body of the stomach. (B) On close-up view, a small opening (arrow) is seen at the center. (C) On narrow-band imaging, the tumor is covered by normal gastric mucosa. (D) When the biopsy forceps is inserted into the opening, the forceps goes in deep. Therefore, it is possible to obtain the core tissue inside the tumor.
Fig. 2(A, B) Endoscopic ultrasonography shows an about 30-mm heterogeneously hypoechoic mass in the third, fourth, and fifth layers. Its margins are lobulated and indistinct, and anechoic duct-like structures (arrow) are seen.
Fig. 3Abdominal computed tomography (CT) findings. (A) On initial CT, a plaque-like mass (arrow) is seen at the posterior wall of the gastric lower body. (B) On CT during acute pain attack after the endoscopic biopsy, an enlargement of the subepithelial tumor (white arrow) and diffuse gastric wall edema are seen. The pancreas is normal (black arrow). When compared with the previous CT image, its density is more hypodense than that of the pancreas. These findings suggest the occurrence of acute ectopic pancreatitis.
Fig. 4Pathological findings. (A) Irregularly arranged lobules of pancreatic acinar and dilated ducts are seen in the submucosa (H&E stain, ×40). (B) Acinar cells contain abundant granular eosinophilic cytoplasm in the apical aspect, with basal basophilic cytoplasm. Nuclei are basally located (H&E stain, ×400).