Pancreatic intraepithelial neoplasia-3 with localized acute pancreatitis in the main pancreatic duct.

Pancreatic intraepithelial neoplasia (PanIN) is one of the most important issues for the early detection of pancreatic ductal adenocarcinoma. In particular, PanIN-3 is recognized as a precancerous lesion, e.g., carcinoma in situ, high-grade dysplasia, and severe dysplasia. We report a rare, completely resected case of PanIN-3 in the main pancreatic duct (MPD) detected from localized pancreatitis. A 63-year-old man developed upper abdominal pain with hyperamylasemia. He underwent distal pancreatectomy soon after recovery because an abnormal narrow segment, suggesting PanIN, was identified in the pancreatic body by endoscopic retrograde cholangiopancreatography. Histopathological findings revealed a PanIN-3 located in the MPD that could be resected completely. This finding suggests that if unidentified localized pancreatitis develops, we should carefully examine the fine structural changes in the MPD.