A resected case difficult in distinguishing invasive adenocarcinoma derived from IPMN from usual pancreatic cancer coexisting with IPMN -introduction of genomic exploration-

Abstract

A 59-year-old man, who had been diagnosed as branched-type IPMN preoperatively, underwent pancreatoduodenectomy. The IPMN consisted of adenoma, adenocarcinoma in situ, slight and sporadic parenchymal invasion and nodal involvement on pathological examination. Continuous transition from the intraductal component to slight parechymal invasion could not be proven, so mutation of codon12 of K-ras gene was investigated in each representative part of the specimen. The allele of the normal ductal epithelium was wild-type GGT (Gly), but the same mutated allele GGT (Gly)→CGT (Arg) was detected in adenoma, adenocarcinoma in situ, and nodal involvement. Although gene amplification in the slight parenchymal invasive cancer cluster failed, we strongly inferred the current case as invasive cancer derived from IPMN. This method may be available for the strict diagnosis of invasive cancer derived from IPMN difficult to pathologically distinguish from usual pancreatic cancer coexisting with IPMN, and its correlation with pathological findings must be validated in many cases.