pyopneumothorax
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.
Clinical presentation
The patient usually presents with chest pain and fever. Cough and breathing difficulty may be present.
Pathology
Etiology
As with a hydropneumothorax, it has a range of causes:
- thoracentesis
- thoracic trauma
- bronchopleural fistula
- esophagopleural fistula
Many causative organisms have been implicated including Mycobacterium tuberculosis, anaerobes, bacteria and fungi.
Radiographic features
Plain radiograph
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.
Ultrasound
Fine internal echoes in the pleural collection strongly suggests infected fluid in appropriate clinical settings.
CT
CT will clearly depict the location of the collection as well as thickening of pleura and underlying disease process (if any).
Treatment and prognosis
Large collections require intercostal drainage with antibiotics.
Differential diagnosis
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.)