​Extensive high-grade PanIN of the main pancreatic duct requiring total pancreatectomy diagnosed after long-term surveillance.

backgroundHigh-grade pancreatic intraepithelial neoplasia (PanIN) is a non-invasive precursor of invasive pancreatic ductal adenocarcinoma. Owing to the absence of mass formation and the limited sensitivity of cytology, the diagnosis and determination of surgical margins remain difficult. CASE PRESENTATION: A 64-year-old woman was referred for the evaluation of progressive pancreatic ductal dilation without an obvious mass lesion. Magnetic resonance cholangiopancreatography revealed main pancreatic duct (MPD) irregularities and partial pancreatic parenchymal atrophy. Long-term surveillance revealed progressive pancreatic atrophy, with substantial dilation of the MPD in the tail of the pancreas. Although the cytological examination was inconclusive, the imaging findings raised the suspicion of high-grade pancreatic intraepithelial neoplasia (HG PanIN). The patient underwent distal pancreatectomy; however, the resection margin was positive for HG PanIN. Total pancreatectomy was subsequently performed. The final histopathological examination revealed high-grade PanIN extending 45 mm (body) and 55 mm (head) along the MPD. The patient's recovery was uneventful and she remained disease-free 5 years post-surgery.

conclusionWe report the importance of recognizing subtle imaging features suggestive of high-grade PanIN and the need for comprehensive surgical planning to ensure curative resection.