Tuberculous Empyema

General Considerations

• Represents a chronic, active infection of the pleural space
• The empyema contains many tubercle bacilli
• Empyemas are rare compared to reactive effusions in TB
• They result from numerous organisms spilling into pleural space
  • Usually from rupture of a cavity, or
• Via a bronchopleural fistula
• Incidence of empyemas was historically higher in the pre-anti-tuberculous agent period when treatments for TB included therapeutic pneumothoraces, oleothorax, ping-pong ball plombage,  pneumonectomy or thoracoplasty

Clinical Findings

• Frequently asymptomatic and found on routine surveillance, or when patient develops either:
  • Bronchopleural fistula
• Empyema necessitatis
• Pleural fluid in the empyema is thick and usually grossly purulent
• Smear is positive for acid-fast bacilli
• May TB empyemas contain cholesterol causing the mistaken gross impression that they are composed of chyle 

Imaging Findings

• Thickened pleural rind, frequently calcified
• Almost always unilateral
• May have an associated extrapleural mass (empyema necessitatis)
• A collection of inflammatory tissue that spontaneously ruptures through a weakness in the chest wall into surrounding soft tissues.
• Can be caused by many infectious agents but mycobacteria are most common cause
• Usually associated with some evidence of parenchymal TB
• Tuberculous empyema is suspected on CT when there is a thick, calcific pleural rind, especially if there is associated rib thickening adjacent to the loculated pleural fluid 

Differential Diagnosis

• Asbestos-related pleural disease causes bilateral pleural plaques
• An old hemothorax may calcify 

Treatment

• Therapy is usually via surgery using
• Parietal decortication, thoracoplasty, with or without omentopexy/myoplasty
• Antituberculous drug therapy is mandatory to sterilize all residual TB

Complications

• Bronchopleural fistula
• Empyema necessitatis
• Inability to re-expand the trapped lung and difficulty in achieving therapeutic drug levels in pleural fluid

Tuberculous Empyema. A frontal radiograph of the chest demonstrates a thick and irregular rind of calcified pleura (yellow arrows) in the right hemithorax with slight shift of the heart and mediastinal structures towards the right due to volume loss. The left hemithorax shows no pleural calcification. This is a typical presentation of a calcified tuberculous empyema.
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