[A case of pancreatic intraepithelial neoplasia-3 with autoimmune pancreatitis].

We report a case of pancreatic intraepithelial neoplasia-3 (PanIN-3) with autoimmune pancreatitis (AIP). The patient, a 75-year-old man, had been diagnosed to have AIP with stenosis of the main pancreatic duct. After six years, computed tomography demonstrated dilatation of the main pancreatic duct in the mid-pancreas. Although we could not confirm the presence of any pancreatic tumor on the basis of imaging modalities alone, cytological examination of the pancreatic juice obtained by endoscopic retrograde pancreatography revealed atypical cells. Therefore, we performed pancreatoduodenectomy and obtained a pathologic diagnosis of PanIN-3 with AIP. The present case is informative in the context of pancreatic carcinogenesis in AIP.