Atezolizumab-induced Encephalitis in a Patient with Hepatocellular Carcinoma: A Case Report and Literature Review

Abstract

We herein report a case of encephalitis in a 42-year-old woman with hepatocellular carcinoma following atezolizumab plus bevacizumab therapy. After two weeks of treatment, she was admitted for a high fever, impaired consciousness, and convulsive seizure refractory to diazepam. Magnetic resonance imaging revealed a hyperintense splenial lesion. A cerebrospinal fluid test excluded malignancy and infection. These findings were highly suggestive of a diagnosis of encephalitis due to atezolizumab, an immune-related adverse event. Steroid pulse therapy improved the fever and seizure. However, her incomplete right-sided paralysis and aphasia persisted. This is the first case report of encephalitis caused by atezolizumab plus bevacizumab therapy for hepatocellular carcinoma.

Keywords: atezolizumab plus bevacizumab; encephalitis; hepatocellular carcinoma; immune-related adverse events; mild encephalitis/encephalopathy with a reversible splenial lesion.

Figure.

(A) Initial brain magnetic resonance imaging (MRI) findings on the first day of intensive care admission. Initial diffusion-weighted MRI revealed a hyperintense signal (blue arrow) in the splenium of the corpus callosum, considered to be consistent with a diagnosis of mild encephalitis/encephalopathy with a reversible splenial lesion. Magnetic resonance angiography showed no abnormal findings or vascular occlusion, and head computed tomography (CT) showed no signs of bleeding. (B) Follow-up diffusion-weighted MRI showed the resolution of the hyperintense signal in the splenium of the corpus callosum. However, a hyperintense signal along the left cerebral cortex remained.