Exacerbation of idiopathic pulmonary fibrosis (IPF) due to treatable causes. (a) High-resolution computed tomography (HRCT) shows minimal evidence of apical interstitial lung disease. (b) HRCT shows, at the lung bases, ground-glass opacities upon extensive peripheral thickening of intralobular septa. The patient was a 65-year-old male with IPF and initiated treatment with high doses of corticosteroids. (c) Four months later, HRCT denotes diffuse ground-glass with irregular reticulation. Note the extensive lipomatosis of the mediastinum due to chronic steroid use. Owing to deterioration of dyspnea, he was admitted to another hospital, where bronchoalveolar lavage (BAL) was performed and the immunosuppressive treatment was intensified. A few weeks later, he was admitted to our department with respiratory failure, severe corticosteroid-related myopathy, diabetes mellitus, severe dyspnea, and purulent sputum. Clinical examination disclosed herpes simplex virus keratitis in the left eye, and BAL cultures grew positive for Pseudomonas aeruginosa. Corticosteroids were tapered, and antimicrobial and antiviral treatment was initiated. Both eye and lower respiratory tract infections subsided, and the patient was discharged home a few weeks later. (d) Eighteen months after the exacerbation, the ground-glass opacities completely resolved as did the lipomatosis of the mediastinum. The patient is still alive and at home.