Acute encephalopathy after postoperative nivolumab therapy for esophageal cancer:posterior reversible encephalopathy syndrome versus immune-related encephalitis

Abstract

Introduction:Neurological immune-related adverse events associated with nivolumab are rare but may pose a diagnostic challenge in postoperative patients, particularly in distinguishing posterior reversible encephalopathy syndrome (PRES) from immune-related encephalitis. Case presentation:A patient who had undergone surgery for esophageal cancer received adjuvant nivolumab therapy and subsequently required emergency surgery for postoperative adhesive small bowel obstruction. Seven hours after surgery, acute disturbance of consciousness developed in the setting of marked hypertension. Brain magnetic resonance imaging (MRI) revealed scattered hyperintense lesions on T2-weighted fluid-attenuated inversion recovery (FLAIR) images that were not strictly posterior-dominant. Given the diagnostic uncertainty between atypical PRES and immune-related encephalitis, a combined therapeutic approach consisting of blood pressure control and systemic corticosteroid therapy was initiated. No further neurological events occurred, and follow-up imaging demonstrated near-complete resolution of the lesions. Conclusion:This case highlights the diagnostic challenge of acute encephalopathy in postoperative patients treated with immune checkpoint inhibitors. Because PRES and immune-related encephalitis may present with overlapping clinical and radiological features, early neuroimaging and a tailored therapeutic approach, including both blood pressure control and immunosuppressive therapy, are essential for appropriate management. J. Med. Invest. 73 : 552-557, August, 2026