Autopsy case of meningoencephalitis induced by nivolumab and ipilimumab in a patient being treated for non-small cell lung cancer.

A 75-year-old woman with stage IVB (cT2bN3M1b) lung adenocarcinoma was administered nivolumab, ipilimumab, carboplatin, and paclitaxel. Fourteen days after receiving chemotherapy, she experienced an impaired consciousness and a cerebrospinal fluid analysis revealed high protein levels and pleocytosis. She was diagnosed with nivolumab- and ipilimumab-induced encephalitis and was treated with corticosteroids which were tapered to 10 mg/day, with no symptom recurrence. She died 18 weeks after the initial presentation, as the cancer worsened. An autopsy showed encephalitis and CD8+ lymphocyte infiltration around the blood vessels. Thus, immune-related adverse events should be suspected and treatment should be initiated for patients presenting with an impaired consciousness when concurrently being treated with nivolumab and ipilimumab.