General group of<unk> s that involve the scarring of lung parenchyma
Grouped together because of similar clinical, physiologic, radiographic, or pathologic findings
Specific<unk> s separated into ones with known causes and idiopathic
Treatment and prognosis differs between specific<unk> s
Examples of specific<unk> s:
Interstitial pneumonia
Hypersensitivity pneumonitis
Cryptogenic organizing pneumonia
Acute interstitial pneumonitis
Sarcoidosis
Idiopathic pulmonary fibrosis
Interstitial pneumonia
Hypersensitivity pneumonitis
Cryptogenic organizing pneumonia
Acute interstitial pneumonitis
Sarcoidosis
Idiopathic pulmonary fibrosis
Interstitial lung disease
Interstitial pneumonias 
Pneumoconiosis
Lung malignancy
Atypical pneumonia
Aspiration pneumonia or pneumonitis
Lung transplant complications
Bacterial, viral, or fungal pneumonia