This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Clinical Aspects of Neoplasia, Subject name: Pathology
Klatskin tumor is - 
Select and explain. 
A. Nodular type of cholangiocarcinoma, B. Fibrolamellar hepatocellular carcinoma, C. Gall bladder carcinoma, D. Hepatocellular carcinoma
A: Nodular type of cholangiocarcinoma
Answer: A: Nodular type of cholangiocarcinoma 
Explanation: Ans. is 'a' i.e., Nodular type of cholangiocarcinoma o Klatskin tumour is an extrahepatic type of cholangiocarcinoma.o According to their localization, cholongiocarcinomas are classified intoIntrahepatic (10-20 %)Extrahepatic (80-90%)o The extrahepaticforms include perihilar tumors known as Klastkin tumors, which are located at the junction of the right and left hepatic ducts forming the common hepatic duct, and distal duct tumors.o A subgroup of distal tumors arise in the immediate vicinity of ampulla of vater. Tumor of these region also include adenocarcinoma of duodenal mucosa and pancreatic carcinoma and are collectively referred to as periampullary carcinomas.