CDKN2A and intrahepatic cholangiocarcinoma: In patients with intrahepatic cholangiocarcinoma, the incidence of FGFR2 rearrangements or fusions is 9−16%, and this is often accompanied by mutational inactivation of tumor protein P53, cyclin‐dependent kinase inhibitor 2A (CDKN2A), or BRCA1 associated protein‐1.196, 197, 198, 199