Azygos fissure


  • An 8 years old boy
  • Presented with fever and cough for one week
  • Clinical examination shows crepitations at right lower zone
Chest radiograph PA erect view

Radiographic findings:

  • There are air space opacities at right lower zone (white arrow). No obliteration of right cardiac margin or right hemidiaphragm is seen.
  • Incidental finding of a curvilinear opacity (yellow arrow) at the right upper zone. This line shows smooth curve from the hilar superiorly towards the chest wall.
  • No hilar mass, no pleural effusion or pneumothorax.

Diagnosis: Pneumonia with incidental finding of azygos fissure

Discussion (azygos fissure/lobe):

  • It is found as an anatomic variant in about 1% of the population.
  • The fissure contains both visceral and parietal pleural layers.
  • On radiograph it is seen as a thin, curvilinear density in the upper right lung, convex towards the chest wall. At its base is the azygos vein which can be seen as a teardrop-shaped structure. The azygos vein will no longer be visible at its normal position at the junction of the trachea and right main bronchus
  • An azygos lobe formed due to invagination of the azygos vein and pleura during development in the fetus. It has no bronchus so is not a true accessory lobe. The size of the lobe is variable
Author: radhianahassan