Successful Management of Rapidly Progressive Interstitial Pneumonia With Autoimmune Features in an Elderly Patient: A Case Report.

An 82-year-old man presented with acute respiratory distress, a one-week history of dry cough, and worsening dyspnea. Chest computed tomography revealed bilateral diffuse ground-glass opacities, raising suspicion of rapidly progressive interstitial pneumonia. Rapid autoantibody testing confirmed interstitial pneumonia with autoimmune features (IPAF), likely triggered by an upper respiratory infection. Initial treatment with high-dose steroid pulse therapy was insufficient to stabilize the patient's respiratory status. Cyclophosphamide pulse therapy was initiated on day 4, resulting in significant improvement by day 7. The patient's oxygen requirements steadily decreased, and follow-up imaging showed near-complete resolution of lung abnormalities. Intensive immunosuppressive therapy, infection control measures, and tailored supportive care enabled functional recovery and discharge to a rehabilitation facility. This case highlights the importance of early diagnosis, rapid immunological evaluation, and aggressive immunosuppressive therapy in managing rapidly progressive interstitial pneumonia in elderly patients. Individualized treatment plans based on overall health rather than biological age can significantly improve outcomes, even in critically ill elderly patients. Early initiation of multidisciplinary care is crucial to achieving remission and restoring quality of life in this challenging population.