pulmonary disorders
Overview of Idiopathic Interstitial Pneumonias
Introduction
Idiopathic interstitial pneumonias (IIPs) are Overview of Interstitial Lung Disease of unknown etiology that share similar clinical and radiologic features and are distinguished primarily by the histopathologic patterns on lung biopsy. Classified into 8 histologic subtypes, all are characterized by varying degrees of inflammation and fibrosis and all cause dyspnea. Diagnosis is based on history, physical examination, high-resolution CT imaging, pulmonary function tests, and lung biopsy. Treatment varies by subtype. Prognosis varies by subtype and ranges from excellent to nearly always fatal. The 8 histologic subtypes of idiopathic interstitial pneumonia, in decreasing order of frequency, are Idiopathic Pulmonary Fibrosis (identified histologically as usual interstitial pneumonia) Desquamative Interstitial Pneumonia None Nonspecific Interstitial Pneumonia None Cryptogenic Organizing Pneumonia None Respiratory Bronchiolitis–Associated Interstitial Lung Disease (RBILD) Acute Interstitial Pneumonia None Lymphocytic Interstitial Pneumonia None Idiopathic Pleuroparenchymal Fibroelastosis None These subtypes are characterized by varying degrees of interstitial inflammation and fibrosis ( General reference ). All cause dyspnea; diffuse abnormalities on high-resolution CT (HRCT); and inflammation, fibrosis, or both on biopsy. The subtypes are important to distinguish, however, because they have different clinical features (see table 