Table 28-3.

Differential Diagnosis for Computed Tomography (CT) Pattern and Rate of Development of Clinical Problem

Predominant CT Pattern	Rate of Progression
	Acute (days)	Subacute (days to weeks)	Chronic (weeks)
Consolidation/focal ground glass infiltration	Bacterial pneumonia Aspiration Diffuse alveolar hemorrhage Acute respiratory distress syndrome (ARDS)*	Cryptogenic organizing pneumonia Aspiration Mycobacteria† Nocardia † Invasive filamentous fungi†	Cryptogenic organizing pneumonia Lymphoma Mycobacteria† Nocardia †
Diffuse ground glass infiltration	CMV pneumonia Viral pneumonia Diffuse alveolar hemorrhage ARDS*	CMV pneumonia PCP Idiopathic pneumonia syndrome (IPS) Drug reactions	Drug reaction
Nodules	Metastatic infection Invasive filamentous fungi	Metastatic infection Invasive filamentous fungi Nocardia Mycobacteria	Lymphoma Lymphoproliferative disease Nocardia Mycobacteria
Multiple nodules (>10)	Metastatic infection	Metastatic infection Mycobacteria	Lymphoma Lymphoproliferative disease Mycobacteria
Bronchiolitis/“tree-in-bud” changes	Viral bronchiolitis Chlamydia pneumoniae Mycoplasma pneumoniae Bacterial exacerbation bronchiectasis	Viral bronchiolitis C. pneumoniae M. pneumoniae Nontuberculous mycobacteria Aspergillus tracheobronchitis† Bacterial exacerbation bronchiectasis	Bronchiectasis Nontuberculous mycobacteria

^*Extensive, patchy, mainly posterior.

^†Usually focal patches.