A case of well-differentiated adenocarcinoma of the duodenal papilla suspected to disseminate from intraductal papillary mucinous carcinoma of the pancreas via pancreatic duct by genetic analysis

Abstract

We report a case of well-differentiated adenocarcinoma of the duodenal papilla which was strongly suspected to disseminate from intraductal papillary mucinous carcinoma (IPMC) via the pancreatic duct by genetic analysis. The patient was an octogenarian male with jaundice. Endoscopic examination revealed mild swelling of the duodenal papilla with sclerosis of the surrounding duodenal wall. A histopathological diagnosis of adenocarcinoma was confirmed by transampullary biopsy, and subtotal stomach-preserving pancreaticoduodenectomy was performed. Pathologically, well-differentiated adenocarcinoma with the gastric phenotype (MUC5AC+, MUC6+) and negative SMAD4-immunoreactivity replaced the epithelium of the ampulla, and invasion was seen into the surrounding stroma. IPMN was found in the branch duct but was microscopically discontinuous with the ampullary tumor. On the contrary, both lesions have same mutations in KRAS G13D and GNAS R201H, which indicated the ampullary carcinoma originated from IPMC lesion and was strongly suspected to disseminate via the pancreatic duct.