An Autoimmune Encephalitis Case Associated with Pembrolizumab Use

Immune checkpoint inhibitors may be associated with various adverse events, including encephalitis. Here, we report a case of encephalopathy associated with pembrolizumab therapy. A 60-year-old male diagnosed with cholangiocarcinoma with peritoneal seeding presented altered mentality and cognitive function after using pembrolizumab. Electroencephalogram showed mild diffuse cerebral dysfunction. Cerebrospinal fluid (CSF) study showed no evidence of infection or autoimmune disease and no paraneoplastic antibody was detected from CSF and serum. After high-dose methylprednisolone intravenous infusion, patient’s mentality was fully recovered.