A Persistent Pneumonia or an Uncommon Condition: A Case of Immunotherapy-Induced Pneumonitis.

Immunotherapy with immune checkpoint inhibitors has revolutionized the treatment of metastatic renal cell carcinoma. However, it may be associated with severe toxicity, particularly immune-mediated pneumonitis. The present case report describes a 60-year-old patient diagnosed with stage IV clear cell renal carcinoma undergoing treatment with nivolumab, who developed severe partial respiratory failure refractory to empirical antibiotic therapy. After exclusion of other causes, namely, cardiovascular and infectious etiologies, immune-mediated pneumonitis was suspected, and systemic corticosteroid therapy was initiated, resulting in significant clinical and radiological improvement. This case illustrates immune-mediated pneumonitis in the context of nivolumab treatment, highlighting the importance of an accurate differential diagnosis in patients receiving immunotherapy and the early initiation of corticosteroid therapy when immune-related pneumonitis is suspected.