Immune Checkpoint Inhibitor-Induced Scleroderma-Like Pulmonary Fibrosis in a Patient With Advanced Lung Cancer: A Case Report.

We describe a 79-year-old man with stage IV non-small cell lung cancer previously treated with pembrolizumab who presented with progressive dyspnea and hypoxemia. Evaluation demonstrated bilateral ground glass opacities with interstitial changes compatible with a nonspecific interstitial pneumonia pattern, echocardiographic findings concerning for pulmonary hypertension, Raynaud phenomenon, and autoimmune serologies including elevated polymyositis/scleroderma 75 (PM/Scl 75) and small nuclear ribonucleoprotein 70 kilodalton (SNRNP 70Kd) antibodies suggestive of a scleroderma-like autoimmune process. Infectious evaluation, including blood and urine cultures and respiratory pathogen testing, did not identify a causative pathogen, although sputum culture, bronchoscopy with bronchoalveolar lavage, and lung biopsy were not performed, which is an important limitation. The patient was treated with broad-spectrum antibiotics, systemic corticosteroids, and ventilatory support, with planned initiation of additional immunosuppressive therapy. Despite these interventions, his respiratory status worsened, requiring mechanical ventilation, and his course was complicated by renal failure, heparin-induced thrombocytopenia, and multiorgan dysfunction. This case illustrates a rare, likely immune checkpoint inhibitor-associated scleroderma-like pulmonary syndrome in a patient with multiple comorbidities and underscores the need to consider progressive autoimmune disease among several potential etiologies in patients presenting with unexplained respiratory decline after immunotherapy, while acknowledging that a definitive causal relationship cannot be established in the absence of a complete diagnostic evaluation.