Name This Lung Pattern

Dear Vets

 

How would you describe this lung pattern?
List your differential diagnoses.

Answer

This patient has an alveolar lung pattern.

When the normally air-filled alveoli become flooded with fluid or cells, the background opacity of the lung changes from a gas lucency to a soft-tissue opacity.

This soft tissue opacity, caused by the accumulated fluid / cells within the alveoli merges with, and therefore obscures, the normal soft tissue markings of the pulmonary vessels and the walls of the airways.

However, the airways themselves are highlighted against the abnormal soft tissue background, and can be identified as branching linear lucencies (arrowed below).  These branching lucencies are known as ‘air bronchograms’ and are the hallmark of an alveolar infiltrate.  This patient has an alveolar lung pattern.

Answer continued

Possible differential diagnoses for an alveolar lung pattern include:

• Pneumonia
• Oedema (cardiogenic or non-cardiogenic)
• Haemorrhage
• Neoplasia

In this patient the location of the changes (within the cranio-ventral lung fields and superimposed on the cardiac silhouette) would be most consistent with aspiration pneumonia.