[Detection of small pancreatic cancer during surveillance of the main pancreatic duct stenosis].

An 83-year-old man with main pancreatic duct (MPD) stenosis in the pancreatic body had undergone surveillance with semiannual imaging studies for 3 years. During surveillance, magnetic resonance cholangiopancreatography revealed gradual enlargement of a small cyst near the MPD stenosis and contrast-enhanced computed tomography revealed locally progressive atrophic parenchyma in the pancreatic body. On endoscopic retrograde pancreatography, the MPD stenosis was more severe than it had been at diagnosis 3 years earlier. Endoscopic ultrasonography (EUS) showed a 10-mm hypoechoic mass adjacent to the MPD stenosis. The mass was pathologically diagnosed as an adenocarcinoma using EUS-guided fine needle aspiration, and distal pancreatectomy was performed. On histopathological examination, the resected specimen was found to be a moderately differentiated 9-mm invasive ductal carcinoma. Additionally, multiple high-grade pancreatic intraepithelial neoplasms (i.e., carcinoma in situ) were detected in the MPD and branch ducts near the invasive carcinoma.