Which of the following is premalignant to cholangiocarcinoma -

Ans. is 'd' i.e., All the above o Premalignant lesions for cholangiocarcinoma are also known, the most important of which are bibary intraepithelial neoplasias (low to high grade, BilIN-1, -2, or -3).o BilIN-3, the highest grade lesion, incurs the highest risk of malignant transformation.o More rare are mucinous cystic neoplasms and intraductal papillary biliary> neoplasia