IDH-mutant tumors have aberrant production and accumulation of the oncometabolite 2-hydroxyglutarate (2-HG), which may play a pivotal oncogenic role in several malignancies. Mutations in IDH1 and IDH2 have been reported in intrahepatic cholangiocarcinomas. IDH1 mutation has been associated with highly elevated tissue levels of the enzymatic product 2-hydroxyglutarate. IDH1 mutation has been described to be a feature of intrahepatic cholangiocarcinomas.