Pembrolizumab‐induced secondary sclerosing cholangitis in a non‐small cell lung cancer patient

A 50‐year‐old woman with stage IV lung adenocarcinoma received seven cycles of pembrolizumab as third‐line chemotherapy. Following the failure of pembrolizumab, she commenced fourth‐line chemotherapy of docetaxel and ramucirumab. The patient complained of epigastric pain and a computed tomography (CT) scan revealed oedema‐like thickening of the gallbladder wall, dilation of the bile ducts from the common to the intrahepatic bile ducts, and thickening of the common bile duct wall without any visible obstructions. Accumulation of fluorodeoxyglucose (FDG) in the gallbladder wall and bile duct was also detected with positron emission tomography (PET)‐CT. A biopsy of the extrahepatic bile duct showed non‐specific inflammation. Antibiotic treatment was not effective and pathogens were not detected. The patient was diagnosed with secondary sclerosing cholangitis (SSC) by pembrolizumab. She received 80 mg/day of prednisolone (PSL); however, SSC recurred with tapering of PSL. SSC then improved with steroid pulse therapy and subsequently 50 mg/day azathioprine and 80 mg/day PSL.