IDH1 and intrahepatic cholangiocarcinoma: Hotspot mutations of IDH1/2 have been identified in various human malignancies, including diffuse gliomas, myelodysplastic syndrome (MDS), chondrosarcoma, intrahepatic cholangiocarcinoma (ICC), and acute myeloid leukemia (AML) [17,61,63,64,65,66].