PD-L1阻害薬で，びまん性の胆管拡張を呈したirAEによる肝障害の2例

Two cases of liver damage of ir-AE induced by PD-L1 inhibitors with diffuse bile duct dilatation

免疫チェックポイント阻害薬（ICI）には免疫関連有害事象（irAE）と総称される，ほかの全身療法にはみられない有害作用の存在が認知されている。

Case1：A 83-year-old man with lung cancer was treated with atezolizumab. After 4 months, he complained general malaise. A blood examination revealed elevation of liver enzyme. Abdominal CT and MRCP revealed diffuse bile duct dilatation without any obstruction.

Case2：A 43-year-old man with lung cancer was treated with durvalumab. After 2 weeks, he complained epigastric pain. A blood examination revealed elevation of liver enzyme. Abdominal CT revealed diffuse bile duct dilatation without any obstruction.

There are few previous reports that ir-AE by PD-1 inhibitor showed bile duct dilatation without obstruction on image examination. We reported similar image features in those two patients. This may be characteristic image feature of ir-AE.