A case of small-cell lung cancer with durvalumab-induced encephalitis presenting as altered behavior

Abstract

A 72-year-old man with small cell lung cancer developed various altered behaviors during chemotherapy, including durvalumab. Although a primary psychiatric disorder was initially suspected, electroencephalography demonstrated generalized slow-wave activity. Because the symptoms rapidly resolved following corticosteroid therapy, he was diagnosed with immune-related encephalitis. Cerebrospinal fluid examination demonstrated positivity for anti-Hu antibodies. This case highlights that immune-related encephalitis should be considered in patients receiving immune checkpoint inhibitors who present with altered behavior, and that early initiation of immunosuppressive therapy may be crucial for clinical improvement of altered behavior.