Anti programmed death-ligand 1 antibody-related cholangitis without bile duct dilation or stenosis.

Cholangitis has been reported as an immune-related adverse event, although it rarely occurs. Here we report a case of cholangitis due to atezolizumab in a 77-year-old woman who had been treated with atezolizumab and nab-paclitaxel for breast cancer and lung metastasis. On the seventh cycle, she presented with fever and epigastric pain, and computed tomography and endoscopic ultrasound showed slight wall thickening of the common bile duct, and transpapillary bile duct biopsy was performed. Pathologically, CD8+ T cells predominant infiltration was detected in the subepithelium of the bile duct, resulting in the diagnosis of atezolizumab-related cholangitis. The patient's symptoms were resolved immediately after discontinuing atezolizumab. Hepatobiliary enzymes returned to normal 21 days after onset, and bile duct wall thickening disappeared. Cholangitis should be included as the differential diagnosis of liver dysfunction in patients receiving immune checkpoint inhibitors.