Poorly Differentiated Adenocarcinoma with Signet-ring Cell Carcinoma of the Extrahepatic Bile Duct in a 42-year-old Japanese Female: A Case Report

Poorly differentiated adenocarcinoma without papilla or tubule formation of the extrahepatic bile duct is rare. Here we present a case (a 42-year-old Japanese woman) without either pancreatobiliary maljunction or liver disease. The patient had obstructive jaundice. Imaging studies revealed a bile duct tumor obstructing the common bile duct and invading the surrounding tissues. Pathologic examination revealed a dense periductal growth of poorly differentiated adenocarcinoma containing signet-ring cells, but without papilla or tubule formation in the extrahepatic bile duct. The tumor cells directly invaded the pancreatic parenchyma and the portal vein. In the extrahepatic bile duct, poorly differen-tiated adenocarcinoma may be established as a distinct clinicopathologic entity if the tumors are characterized by: 1) the absence of papilla or tubule formation, 2) Asian preponderance, 3) occur-rence at a younger age than is usual for patients with biliary cancers, and 4) an aggressive mural invasiveness. Key words: adenocarcinoma, bile duct cancer, signet-ring cell carcinoma lthough a poorly differentiated carcinoma com-ponent is usually admixed with better-differen-tiated carcinomas in cancers of the extrahepatic bil