[A Case of Adenocarcinoma Arising from an Ectopic Pancreas of the Stomach Presenting as Pyloric Stenosis].

The patient was a 37-year-old man who visited a neighborhood clinic complaining of nausea and upper abdominal pain. Since examination revealed abdominal distention, he was referred to our hospital. Abdominal computed tomography at our hospital revealed retention of gastric contents and contrast-enhancing wall thickening localized to the pyloric region. Upper gastrointestinal endoscopy showed stenosis involving the entire circumference of the pylorus. However, multiple biopsies failed to reveal any evidence of malignancy. Four dilatations were performed, with no improvement. Therefore, the patient was referred to the Department of Surgery. Since malignant disease could not be ruled out, laparoscopic distal gastrectomy with D2 lymph node dissection was performed. Histopathological examination of the resected specimen revealed the presence of ectopic pancreatic tissue in the proper muscle layer of the pylorus. Adenocarcinoma invading and proliferating into the surrounding ectopic mucosal lesion was observed. Therefore, the patient was diagnosed with adenocarcinoma arising from ectopic pancreas. The possibility of ectopic pancreatic cancer may need to be considered in patients with pyloric stenosis caused by a submucosal tumor-like lesion.