BACKGROUND: High-grade pancreatic intraepithelial neoplasia(Pan IN-3), a precursor of pancreatic ductal adenocarcinoma(PDAC), is not universally detected in resected pancreatic neoplasms. We sought to determine the prevalence and prognostic relevance of Pan IN-3 lesions in primary surgical resections of PDACs and intraductal papillary mucinous neoplasms(IPMNs).METHODS: A retrospective review of a tertiary care center pathology database(1/2000-6/2014) was performed. Demographics, imaging, pathology, disease-recurrence, and survival data were reviewed.RESULTS: A total of 458 patients who underwent primary pancreatic resection were included. “Pan IN-3” lesions were found in 74(16.2%) patients who either had PDAC(n=67) or main duct(MD)-IPMN(n=7). Among IPMN-MDs, Pan IN-3 lesions were exclusively found in those with pathological evidence of chronic pancreatitis. For PDACs, the median overall survival(OS) for pancreata with Pan IN-3 lesions was significantly better than those without(OS 1.12 years, interquartile range [IQR] 0.72, 2.05 years vs OS 0.86 years, IQR 0.64,1.60 years respectively; P=0.04). Multivariate Cox regression analysis demonstrated that the presence of Pan IN-3 lesions was associated with a reduced risk of death(HR=0.43; 95% CI: 0.23-0.82; P=0.01).CONCLUSIONS: Following primary resection of pancreatic adenocarcinoma, the lower survival observed in patients without Pan IN-3 lesions might suggest a state of complete or accelerated transformation. Further investigations are necessary to validate these findings that might impact disease prognosis and management. BACKGROUND: High-grade pancreatic intraepithelial neoplasia (Pan IN-3), a precursor of pancreatic ductal adenocarcinoma (PDAC), is not universally detected in resected pancreatic neoplasms. We sought to determine the prevalence and prognostic relevance of Pan IN-3 lesions in primary surgical resections of PDACs and intraductal papillary mucinous neoplasms (IPMNs). METHODS: A retrospective review of a tertiary care center pathology database (1 / 2000-6 / 2014) was performed. Demographics, imaging, pathology, disease-recurrence, and survival A total of 458 patients who underwent primary pancreatic resection were included. “Pan IN-3 ” lesions were found in 74 (16.2%) patients who either had PDAC (n = 67) or main duct For IPACs, the median overall survival (OS) for pancreata with Pan IN-3 lesions was significantly better than those without (OS 1. 12 years, interquartile range [IQR] 0.72, 2.05 years vs OS 0.86 years, IQR 0.64, 1.60 years respectively; P = 0.04). Multivariate Cox regression analysis demonstrated that the presence of Pan IN-3 lesions was associated with a reduced risk of CONCLUSIONS: Following primary resection of pancreatic adenocarcinoma, the lower survival observed in patients without Pan IN-3 lesions would suggest a state of complete or accelerated transformation. (HR = 0.43; 95% CI: 0.23-0.82; Further investigations are necessary to validate these findings that might impact disease prognosis and management.