Chapter 136: Interstitial Lung Disease

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: Sarcoidosis. 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 136-1: Major Categories of Alveolar and Interstitial Inflammatory Lung Disease
Lung response: Alveolitis, interstitial inflammation, and fibrosis
Known Cause
 Aspiration pneumonia
Drugs (e.g., nitrofurantoin, amiodarone, methotrexate, rituximab) and chemotherapy drugsResidual of adult respiratory distress syndrome


 Desquamative interstitial pneumonia

 Respiratory bronchiolitis-associated interstitial lung disease

 Langerhans cell granulomatosis (eosinophilic granulomatosis of the lung)

Unknown Cause
Idiopathic interstitial pneumoniasPulmonary alveolar proteinosis
 Idiopathic pulmonary fibrosis (usual interstitial pneumonia)Lymphocytic infiltrative disorders (lymphocytic interstitial pneumonitis associated with connective tissue disease)
 Eosinophilic pneumonias
 Acute interstitial pneumonia (diffuse alveolar damage)




 Cryptogenic organizing pneumonia (bronchiolitis obliterans with organizing pneumonia)

 Nonspecific interstitial pneumonia

Inherited diseases

 Tuberous sclerosis, neurofibromatosis, Niemann-Pick disease, Gaucher disease, Hermansky-Pudlak syndrome

Connective tissue diseases

 Systemic lupus erythematosus, rheumatoid arthritis, systemic sclerosis, Sjögren syndrome, polymyositis-dermatomyositis

Gastrointestinal or liver diseases (Crohn disease, primary biliary cirrhosis, chronic active hepatitis, ulcerative colitis)


Graft-versus-host disease (bone marrow transplantation; solid organ transplantation)

Pulmonary hemorrhage syndromes

 Goodpasture syndrome, idiopathic pulmonary hemosiderosis, isolated pulmonary capillaritis

Lung response: Granulomatous
Known Cause
Hypersensitivity pneumonitis (organic dusts)Inorganic dusts: beryllium, silica
Unknown Cause
SarcoidosisBronchocentric granulomatosis
Granulomatous vasculitidesLymphomatoid granulomatosis
Granulomatosis with polyangiitis (Wegener’s), allergic granulomatosis of Churg-Strauss 

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