Abstract
Immune checkpoint inhibitors, including nivolumab, can result in immune-related adverse events (irAEs) that may affect multiple organ systems. Among irAEs, both gastritis and cholangitis are uncommon. We present the case of a 65-year-old man who received nivolumab for lung adenocarcinoma presented with epigastric pain. He was diagnosed with immune-related gastritis and cholangitis based on imaging and pathological findings. We administered prednisolone (1 mg/kg/day), which improved the patient's gastritis and relieved his pain. However, he experienced recurrent epigastric pain during corticosteroid tapering, and magnetic resonance imaging showed biliary tract hemorrhage. After watchful waiting, the hemorrhage improved without additional immunosuppressants. Immune-related gastritis, immune-related cholangitis, and their coexistence should be considered in patients who develop epigastric pain during immune checkpoint inhibitor therapy. When patients with concurrent immune-related gastritis and cholangitis complain of recurrent epigastric pain, it is important to assess which of these two irAEs is worsening because the optimal immunosuppressants differ between the two.