Azygos lobe without azygos vein as a sign of previous iatrogenic pneumothorax: two case reports.

Background: A spontaneous pneumothorax appears to be rarely seen in patients with an azygos lobe, although this normal variant is incidentally found on CT and chest X-ray. The displacement of the azygos vein from the azygos lobe to the paramediastinal position indicates previous pneumothorax.

Methods: We report two patients (a 59 and a 27-year-old female) where the finding of an azygos lobe without an azygos vein proved to be a sign of previous iatrogenic pneumothorax.

Conclusions: Documentation of an azygos lobe without azygos vein is highly suggestive of a previous pneumothorax. This observation may indicate an iatrogenic cause, because of the possible protective effect of an azygos lobe to the occurrence of spontaneous pneumothorax.