Diagnosis of exclusion
Presentations with rapid deterioration without obvious cause common
May co-exist with<unk>  hypertension and heart failure
Diagnosis of<unk> 
Unexplained worsening of dyspnea within 30 days
Hypoxemia deviated from baseline ABG
No evidence of<unk>  infection
Exclusion of alternative causes (i.e. VTE)
CT with bilateral ground-glass abnormalities/consolidation on a background reticular/honeycomb pattern consistent with interstitial pneumonia
100% have bilateral ground-glass opacities
~70% have consolidation
100% have bilateral ground-glass opacities
~70% have consolidation
Idiopathic pulmonary fibrosis
Interstitial pneumonias 
Bronchiectasis
Lung malignancy
Sarcoidosis
Aspiration pneumonia or pneumonitis
CMV pneumonia
Bacterial, viral, or fungal pneumonia