In combined IOPN cases, immunohistochemistry for FST was different between the IOPN area and other IPMN/IPNB components; IOPN components were weakly or intensely positivity for FST, whereas other components were negative or weakly positive for FST (Fig. 3j,k). This evidence concerns the gene FST and pancreatic intraductal papillary-mucinous neoplasm.