Homogeneous opacity obscuring vessels
Ill-defined or fluffy opacities
“Acinar” or air-space nodules
Preserved lung volume
Extension to the pleural surface
“CT angiogram” sign
5 to 10 mm in diameter, that occur due to focal consolidation (Fig. 2-5). Although these nodules approximate the size of acini, they tend to be centrilobular and peribronchiolar rather than acinar. They may be seen as the only finding of consolidation or may be seen in association with larger areas of consolidation, usually at the edges of the more abnormal lung.
Water (e.g., the various types of pulmonary edema)
Blood (e.g., pulmonary hemorrhage)
Pus (e.g., pneumonia)
Cells (e.g., bronchioloalveolar carcinoma, lymphoma, eosinophilic pneumonia, organizing pneumonia [bronchiolitis obliterans organizing pneumonia or BOOP], hypersensitivity pneumonitis)
TABLE 2.1 Differential Diagnosis of Diffuse Consolidation
Water (edema) (see Chapter 11)
Hydrostatic (cardiogenic) pulmonary edema
Left atrial or pulmonary venous obstruction
Low intravascular oncotic pressure
Increased permeability (noncardiogenic) pulmonary edema
With diffuse alveolar damage (acute respiratory distress syndrome [ARDS])
Acute interstitial pneumonia
Aspiration of gastric acid
Infection and sepsis
Toxic fumes or gases
Without diffuse alveolar damage
Any cause of ARDS, in a mild form
Hantavirus pulmonary syndrome
Mixed types of edema
High-altitude pulmonary edema
Neurogenic pulmonary edema
Hydrostatic and permeability edema
Blood (hemorrhage) (see Chapter 19)
Aspiration of blood
Collagen-vascular disease and immune complex vasculitis
Systemic lupus erythematosus most common
Idiopathic pulmonary hemosiderosis
Pneumonia in an immunosuppressed patient
Fungal pneumonia (histoplasmosis, aspergillosis most common)
Lymphoma and other lymphoproliferative diseases
Eosinophilic pneumonia or other eosinophilic diseases
Organizing pneumonia (BOOP)
Idiopathic interstitial pneumonias
Nonspecific interstitial pneumonia
Desquamative interstitial pneumonia
Alveolar proteinosis (lipoprotein)
Lipoid pneumonia (lipid)
Other substances (e.g., lipoprotein in alveolar proteinosis, lipid in lipoid pneumonia).
Nonetheless, several patterns of diffuse consolidation may suggest possible causes.
FIG. 2.8. Perihilar “bat-wing” consolidation in pulmonary edema. A: Chest radiograph shows a distinct perihilar predominance of consolidation. The heart is enlarged. B: CT shows sparing of the lung periphery.
viral pneumonia (cytomegalovirus [CMV], measles), endobronchial spread of bronchioloalveolar carcinoma, pulmonary hemorrhage, or sometimes aspiration.
eosinophilic pneumonia; atelectasis; or rarely focal edema. The appearance of focal consolidation may also result from confluent interstitial disease, as in patients with sarcoidosis. The appearance or pattern of focal or multifocal consolidation may be helpful in differential diagnosis.
TABLE 2.2 Differential Diagnosis of Focal Consolidation
myocardial infarction resulting in papillary muscle rupture and mitral valve prolapse; it occurs because a jet of regurgitant blood is directed into the right superior pulmonary vein. Focal pulmonary hemorrhage may lead to a lobar consolidation. Lobar consolidation is uncommon with pulmonary embolism.
sphere of consolidation as more and more alveoli become involved. As the growing sphere reaches a pleural surface or fissure and cannot spread further, it becomes lobar.
FIG. 2.16. (Continued.) C: Typical findings of right upper lobe consolidation: (1) obscuration of the right superior mediastinum, (2) obscuration of the superior right hilum, and (3) opacity marginated inferiorly by the minor fissure.
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