Intrahepatic cholangiocarcinoma with FGFR2 fusion gene positive that responded to pemigatinib and caused hypophosphatemia.

Intrahepatic cholangiocarcinoma is a condition with a poor prognosis. Traditionally, there was no cure unless important drugs such as gemcitabine, cisplatin, and tegafur/gimeracil/uracil potassium showed efficacy. Pemigatinib has recently become accessible for the treatment of intrahepatic cholangiocarcinoma with FGFR2 fusion or rearrangement gene abnormalities. Hyperphosphatemia is typically linked to pemigatinib. In the current case, pemigatinib was used to effectively treat a 48-year-old woman, and hypophosphatemia was observed. Patients with intrahepatic cholangiocarcinoma should undergo aggressive cancer multigene panel testing as well as careful monitoring of serum phosphorus levels.