Last revised by Bahman Rasuli on 22 Apr 2021

Pyopneumothorax (also known as infected hydropneumothorax or empyemic hydropneumothorax) is a pleural collection of pus and gas. It may be thought of a variant of a thoracic empyema with gas-containing components although the etiology may be different.

The patient usually presents with chest pain and fever. Cough and breathing difficulty may be present.

As with a hydropneumothorax, it has a range of causes:

Many causative organisms have been implicated including Mycobacterium tuberculosis, anaerobes, bacteria and fungi.

A gas-fluid level is noted. It may be loculated. Loss of silhouette with the dome of diaphragm may be seen. It may be difficult to differentiate a pyopneumothorax from non-infected hydropneumothorax. Presence of thick pleural lining strongly favors the former.

Fine internal echoes in the pleural collection strongly suggest infected fluid in appropriate clinical settings.

CT will clearly depict the location of the collection as well as thickening of pleura and underlying disease process (if any).

Large collections require intercostal drainage with antibiotics.

On imaging consider

  • non-infected hydropneumothorax (no pleural thickening)
  • peripheral lung abscess
  • previous empyema with iatrogenic introduction of air (e.g. drain insertion or diagnostic aspiration etc.)

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