Spontaneous pneumothorax and a coexistent azygos lobe.

We present a primary spontaneous pneumothorax involving a possible diagnostic and surgical pitfall. A 25-year-old man with a previously identified azygos lobe was admitted to our hospital because of right primary spontaneous pneumothorax. A preoperative chest X-ray at the onset of the pneumothorax as well as after resolution by tube drainage showed an azygos fissure but no azygos vein. Chest computed tomography revealed the dislocated azygos vein external to the azygos fissure on the mediastinal side of the reexpanded upper lobe. Thoracoscopic bullectomies were uneventfully performed. The azygos arch was found dangling in the free inferior border of the mesoazygos. An azygos vein located in this position can be a potential surgical hazard especially in video-assisted thoracic surgery. This case suggests that the presence of an azygos lobe can be missed on chest X-ray when a pneumothorax occurs in a patient with an azygos lobe.