Immune Checkpoint Inhibitor-Related Aortitis Treated with Nivolumab for Esophageal Squamous Cell Carcinoma

Although immune-related adverse events (irAEs) associated with immune checkpoint inhibitors (ICIs) are widely recognized, ICI-related aortitis is very rare and challenging to diagnose.

A 70-year-old man with esophageal squamous carcinoma recurring after esophagectomy received paclitaxel therapy after nivolumab therapy. Nivolumab therapy was administered for 26 months; however, no adverse events occurred during treatment. One month after the initiation of paclitaxel therapy, the patient developed a fever lasting for 2 weeks. Thoracoabdominal contrast-enhanced computed tomography (CT) revealed aortic wall thickening and increased fat density in the descending thoracic aorta; however, no other cause of inflammation was detected. Further examination ruled out infectious or autoimmune disease, and the patient was eventually diagnosed with ICI-related aortitis. Methylprednisolone was administered intravenously at a dose of 80 mg, and the fever subsided on the second day after administration. As the inflammation improved, methylprednisolone was switched to oral prednisolone, and the dose was gradually tapered without symptom relapse. Two months after diagnosis, a follow-up CT scan confirmed the resolution of both aortic wall thickening and the increased fat density.

ICI-related aortitis should be considered as a differential diagnosis for unexplained fever after ICI administration.