CDH17+/CDX2+ Can be Helpful in Providing Support for Small Intestinal Origin Versus Pancreatic or Biliary Origin.

Because of the distinct and complex anatomy of the ampullary region, the exact origin of the periampullary tumors was often difficult to ascertain. In this study, we evaluated 78 patient samples, including 26 small intestinal adenocarcinomas, 35 pancreatic ductal adenocarcinomas, and 17 cholangiocarcinomas by immunohistochemical detection of cadherin-17 (CDH17), CDX2, CK20, and CK19 protein expression. The result showed that CDH17 and CDX2 expression was higher in small intestinal adenocarcinoma (73.1% and 65.4%) than in pancreatic (14.3% and 2.9%) and bile duct (41.2% and 23.5%) cancers, respectively. CK20 expression was low in 78 tumor tissues, but relatively high in small intestinal adenocarcinoma (42.3%). CK19 showed a strong positive expression in all 78 adenocarcinoma tissues. The CDH17-high/CDX2-high pattern was predominantly expressed in small intestinal cancer tissues (75%), whereas the CDH17-low/CDX2-low pattern was observed in pancreatic cancers (63.8%) and bile duct cancers (20.9%). The study concluded that CDH17-high/CDX2-high adenocarcinomas more likely originated from small intestine versus pancreas or bile duct, whereas CDH17-low/CDX2-low ones are more likely of pancreatic origin. The combined use of CDH17 and CDX2 could be helpful in providing support for the histologic origin of periampullary adenocarcinoma.