Supplementary Material for: Pegfilgrastim-induced aortitis in a patient with small-cell lung cancer who received immunotherapy combined with chemotherapy.

Introduction: Granulocyte colony-stimulating factor (G-CSF), including pegfilgrastim, increases the peripheral blood leukocyte count and is widely used in clinical practice in combination with cytotoxic chemotherapy. The most frequent side effects of G-CSF are pain and fever; aortitis, in contrast, is a rare and serious side effect. Case presentation: A 73-year-old man with small-cell lung cancer was treated with a full dose of a combination of carboplatin/etoposide /durvalumab and pegfilgrastim. The patient developed fever and right ear pain 12 days after pegfilgrastim administration and was diagnosed with aortitis by contrast-enhanced computed tomography 5 days later. Because the patient had already been administered the immune checkpoint inhibitor and had a history of hepatitis B, the patient was followed up without corticosteroid administration, and the patient’s symptoms resolved spontaneously. Conclusion: In situations where immunosuppression should be avoided, we believe that follow-up without corticosteroids for G-CSF-induced aortitis is a promising option.