Snapshot A 68-year-old man presents to the emergency department for worsening shortness of breath. His dyspnea was most notable with exertion; however, over the course of the past several months, it presented at rest. He reports that he has a non-productive cough and denies have any sinus pain, fever, malaise, chills, or night sweats. He has a past medical history of hypertension and hyperlipidemia. He is a retired aircraft mechanic and has smoked 1 pack of cigarettes daily for the past 45 years. His temperature is 98.6°F (37°C), blood pressure is 134/90 mmHg, pulse is 106/min, respirations are 23/min, and oxygen saturation is 88% on room air. On physical exam, the patient is alert to person but not place or time. There are rales on pulmonary auscultation and digital clubbing. A chest radiograph demonstrates a reticular pattern and honeycombing. Introduction Definition login to view 1 more bullet Etiology Environmental login to view 8 more bullets Granulomatous disease login to view 4 more bullets Alveolar filling disease login to view 3 more bullets Hypersensitivity lung disease login to view 2 more bullets Drugs login to view 3 more bullets Pathogenesis login to view 2 more bullets Presentation Symptoms and physical exam findings differ depending on the underlying cause; for example, patients with pulmonary sarcoidosis may have erythema nodosum Symptoms login to view 3 more bullets Physical exam login to view 3 more bullets Imaging Chest radiography login to view 5 more bullets High-resolution CT scan of the chest login to view 2 more bullets Studies Pulmonary function tests login to view 3 more bullets Differential Heart failure login to view 2 more bullets Pulmonary embolism login to view 2 more bullets Treatment Of note, treatment is dependent upon the underlying cause Conservative login to view 3 more bullets Medical login to view 6 more bullets Complications Irreversible pulmonary fibrosis Respiratory failure Prognosis Variable and depends on the underlying cause