Fundamental Radiological Findings: Pneumomediastinum

OVERVIEW

This page is dedicated to covering the important radiological finding of a pneumomediastinum. 

WHAT IS IT?

A pneumomediastinum refers to a finding on a chest X-ray where air is found in the mediastinum.

Presence of pneumomediastinum (white arrows) and subcutaneous emphysema (black arrow) in a patient (source).

There can be a few different findings that are described as pneumomediastinum:

  • Linear streak like lucency associated with a thin white line that is alongside the left heart border
  • Streaky air outlining the great vessels (aorta, superior vena cava, carotid arteries)
  • Linear streaks of air parallel to the spine in the upper thorax/neck (surround the esophagus and trachea)
DIFFERENTIAL DIAGNOSIS FOR THIS FINDING

When seeing a pneumomediastinum, it is important to keep in mind the following possible causes of this finding:

  • Rupture of alveoli: can be caused by pulmonary interstitial emphysema
  • Rupture of distal esophagus: this can be secondary to very forceful retching/vomiting (Boerhaave syndrome), instrumentation
  • Rupture of the tracheobronchial tree: iatrogenic causes (traumatic intubation), penetrating wounds, severe blunt trauma.
  • Pneumoperitoneum: secondary to things such as laparoscopy
KEY FEATURES TO LOOK FOR WHEN CHARACTERIZING THE FINDING

When seeing a pneumomediastinum, there are a few important radiological features one should look at to try and characterize the finding. These features can help navigate the differential diagnosis above.

Page Updated: 01.07.2016