Imaging Features of Idiopathic Interstitial Lung Diseases

Idiopathic interstitial pneumonias (IIPs) are a group of diffuse parenchymal lung diseases of unclear etiology and are distinguished from diffuse parenchymal lung diseases of known cause, such as connective tissue disease-related interstitial lung diseases or hypersensitivity pneumonitis by history, physical exam, imaging, serologic testing, and, when necessary, histopathology. The 2013 American Thoracic Society (ATS)/European Respiratory Society (ERS) guidelines are the most widely accepted classification of IIPs and include the following diagnoses: idiopathic pulmonary fibrosis, idiopathic nonspecific interstitial pneumonia, cryptogenic organizing pneumonia, acute interstitial pneumonia, idiopathic lymphocytic interstitial pneumonia, idiopathic pleuro-parenchymal fibroelastosis, respiratory bronchiolitis-interstitial lung disease, and desquamative interstitial pneumonia. The gold standard for diagnosis of IIP involves multidisciplinary discussion among pulmonologists, radiologists, and pathologists. The focus of this review will be to discuss the imaging features of the most common IIPs and the role of multidisciplinary discussion as the gold standard for diagnosis.