Objectives To clarify the usefulness of molecular biomarkers for distinguishing invasive carcinoma derived from intraductal papillary mucinous neoplasms (IPMNs [Inv-IPMN]) from concomitant pancreatic ductal adenocarcinoma (PDAC). Methods Data from 19 patients with resected concomitant PDAC were retrospectively reviewed. KRAS/GNAS mutations and immunohistochemical (IHC) expression of p53 and p16/CDKN2A were assessed in both IPMN and distinct PDAC. As controls, KRAS/GNAS mutations and IHC labeling were assessed between invasive and noninvasive components in 1 lesion of 22 independent patients. Results KRAS/GNAS mutation status of invasive and noninvasive components in Inv-IPMN was consistent in 18 (86%) of 21 patients. Conversely, mutational patterns in IPMN and distinct PDAC in the same pancreas differed from each other in 17 (89%) of 19. There were 10 (53%) and 8 (42%) of 19 patients who showed the same p53 and p16/CDKN2A staining between concomitant PDAC and distinct IPMN. In the Inv-IPMN cohort, 19 (86%) of 22 patients showed the same IHC expression pattern between the noninvasive and invasive components. Conclusions It may be possible to distinguish Inv-IPMN from concomitant PDAC by assessing these molecular biomarkers. More precise distinction of Inv-IPMN and concomitant PDAC will lead to adequate recognition of the natural history of IPMNs and hence optimal management.
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