The Prevalence and Clinicopathological Characteristics of High-Grade Pancreatic Intraepithelial Neoplasia: Autopsy Study Evaluating the Entire Pancreatic Parenchyma.

OBJECTIVE:We sought to identify clinicopathological characteristics of high-grade pancreatic intraepithelial neoplasia (PanIN)/carcinoma in situ to facilitate screening for pancreatic ductal adenocarcinoma. METHODS:We evaluated PanIN lesions in 173 consecutive autopsy cases with no evidence of pancreatic ductal adenocarcinoma and/or intraductal papillary mucinous neoplasm (mean age, 80.5 years) by submitting the entire pancreas for microscopic examination. RESULTS:PanIN-3 was found in 4% of examined cases, whereas PanIN-1 and PanIN-2 were present in 77% and 28%, respectively. PanIN-3 was more frequently identified in patients with diabetes mellitus and/or older age. PanIN-3 lesions were always multifocal, and the number of PanIN-3 foci was positively associated with those of PanIN-1 or PanIN-2. PanIN-3 was located more frequently in the pancreatic body and tail than in the head and predominantly involved small interlobular/intralobular ducts rather than the main duct. Notably, 71% of pancreata with PanIN-3 showed cystic changes in PanIN-3 and lower grade PanIN lesions. PanIN-3 was also accompanied by higher grade extralobular fibrosis. CONCLUSIONS:We found that 4% of the examined pancreata harbored PanIN-3 lesions that were associated with several unique clinicopathological features. The cystic change along with fibrotic pancreatic parenchyma may be detected by imaging studies such as endoscopic ultrasound.