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Interstitial lung diseases (ILDs) are a group of >200 disease entities characterized by diffuse lung parenchymal abnormalities. ILDs can be classified into two major groups: (1) diseases associated with predominant inflammation and fibrosis, and (2) diseases with predominantly granulomatous reaction in interstitial or vascular areas (Table 136-1). ILDs are nonmalignant and noninfectious, and they are typically chronic. The differential diagnosis of ILDs often includes infections (e.g., atypical mycobacteria, fungi), congestive heart failure, and malignancy (e.g., bronchoalveolar cell carcinoma). One of the most common ILDs associated with a granulomatous reaction, sarcoidosis, is discussed in Chap. 169. Other common ILDs include idiopathic pulmonary fibrosis (IPF) and ILDs related to connective tissue diseases. Many ILDs are of unknown etiology; however, some ILDs are known to be associated with specific environmental exposures including asbestos, radiation therapy, and organic dusts.

TABLE 136-1Major Categories of Alveolar and Interstitial Inflammatory Lung Disease


APPROACH TO THE PATIENT Interstitial Lung Disease

History: Common presenting symptoms for pts with ILDs include dyspnea and nonproductive cough. Hemoptysis is uncommon in ILDs and could suggest diffuse alveolar hemorrhage, lymphangioleiomyomatosis (LAM), or granulomatosis with polyangiitis (GPA), as well as a secondary pulmonary infection. Assessment for connective tissue disease symptoms (e.g., Raynaud’s) should be performed. Symptom onset and duration can assist in the differential diagnosis. Chronic symptoms (over months to years) are typically seen in most ILDs, including IPF, pneumoconioses, connective tissue diseases, and pulmonary Langerhans cell histiocytosis (PLCH or eosinophilic granuloma). Subacute symptoms (over weeks to months) can also be observed in many ILDs, especially in sarcoidosis, drug-induced ILDs, and cryptogenic organizing pneumonitis (COP, also known as bronchiolitis obliterans with ...

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