A case of extensive intraepithelial lesions throughout the pancreas with focal high-grade pancreatic intraepithelial neoplasm: implications for diagnosis and surgical strategy.

In the preoperative pathological diagnosis of high-grade pancreatic intraepithelial neoplasia (PanIN), pancreatic juice cytology is commonly used. However, when multiple stenoses are present in the main pancreatic duct (MPD), localizing the tumor can be challenging. Here, we report a case of high-grade PanIN with beaded MPD stenoses and extensive intraepithelial lesions. A 72-year-old man was found to have elevated pancreatic enzymes and cystic MPD dilation on abdominal ultrasonography. Contrast-enhanced computed tomography showed diffuse MPD dilation and localized pancreatic atrophy in the pancreatic head. Magnetic resonance cholangiopancreatography revealed cystic dilation of the MPD in the pancreatic body. Endoscopic ultrasonography showed mild MPD stenosis in the pancreatic head, surrounded by hypoechoic area. Endoscopic retrograde cholangiopancreatography revealed multiple bead-like MPD stenoses in the body of the MPD, and a short stenosis in the pancreatic head. Brush cytology of the MPD stenosis in the pancreatic head revealed malignancy, while lavage cytology from the tail side was suspicious for malignancy. Based on these findings, high-grade PanIN extending from the head to the tail was diagnosed, leading to total pancreatectomy. Histological examination demonstrated extensive intraepithelial neoplastic lesions, with high-grade PanIN corresponding to the MPD stenosis in the pancreatic head.