On a chest x-ray lung abnormalities will either present as areas of increased density or as areas of decreased density.
Lung abnormalities with an increased density – also called opacities – are the most common.
A practical approach is to divide these into four patterns:
- Consolidation – any pathologic process that fills the alveoli with fluid, pus, blood, cells (including tumor cells) or other substances resulting in lobar, diffuse or multifocal ill-defined opacities.
- Interstitial – involvement of the supporting tissue of the lung parenchyma resulting in fine or coarse reticular opacities or small nodules.
- Nodules or masses – any space occupying lesion either solitary or multiple.
- Atelectasis – collapse of a part of the lung due to a decrease in the amount of air in the alveoli resulting in volume loss and increased density.
In this article we will focus on this four-pattern approach.
At the end we will also discuss diseases that present as areas of decreased density.
Here are the most common examples of these four patterns on a chest x-ray.
- Lobar consolidation
- Diffuse consolidation
- Multifocal ill-defined consolidations
- Reticular interstitial opacities
- Fine Nodular interstitial opacities
- Nodule or mass
- Solitary Pulmonary Nodule
- Multiple Masses