Atezolizumab-induced encephalitis with subdural hemorrhage and subarachnoid hemorrhage in a patient with hepatocellular carcinoma.

We report the case of a 76-year-old man who was diagnosed with advanced stage hepatocellular carcinoma and was treated with atezolizumab plus bevacizumab therapy. Two weeks after 1st dose, he presented with acute changes in consciousness followed by hypothermia. A cerebrospinal fluid test showed an elevated cell count, total protein, and albumin. Infectious, anatomical, endocrinal, and neoplastic etiologies were ruled out. Based on the findings, atezolizumab-induced encephalitis was suspected, and high dose steroid therapy was administered. The patient's conscious level and hypothermia recovered completely about 9 days after starting the steroids, and he recovered without any neurological sequelae. This case report reminds physicians that prompt administration of steroid treatment after early diagnosis of immune checkpoint inhibitor-related encephalitis is the key for patients to recover without apparent neurological sequelae.