Intrahepatic bile duct injury as a hepatic immune-related adverse event after immune-checkpoint inhibitor treatment

The increased use of immune-checkpoint inhibitors to treat various types of cancer has increased the incidence of immune-related adverse events (irAEs). Hepatic irAEs are frequent and can lead to serious conditions. Among the various types of hepatic irAEs reported to date, bile duct injury has been shown refractory to steroid treatment. This study describes 2 patients with hepatic irAEs manifesting as intrahepatic bile duct injury. Immunostaining with antibodies to both CD8 and cytokeratin-7 was useful for the diagnosis, and both patients were refractory to steroid treatment. Prompt diagnosis and active immunosuppressive therapies are required in such cases.