Empyema vs pulmonary abscess

Distinguishing between an empyema and a peripherally located pulmonary abscess is essential.

Lung abscesses are usually managed with prolonged antibiotics and physiotherapy with postural drainage whereas an empyema usually requires percutaneous or surgical drainage.

Radiographic features

Plain radiograph
  • shape
    • abscess is usually round in all projections
    • an abscess may form an acute angle with the costal surface / chest wall
    • empyema is usually lentiform
CT
  • relationship to adjacent bronchi/vessels
    • abscesses will abruptly interrupt the bronchovascular structures
    • empyema will usually distort and compress adjacent lung
  • split pleura sign
    • thickening and separation of visceral and parietal pleura is a sign of empyema
  • wall
    • abscesses have thick irregular walls
    • empyema are usually smoother
  • angle with pleura
    • abscesses usually have an acute angle (claw sign)
    • empyema have obtuse angles
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Article Information

rID: 8596
System: Chest
Section: Approach
Synonyms or Alternate Spellings:
  • Empyema vs lung abscess
  • Lung abscess vs empyema
  • Pulmonary abscess vs empyema
  • Empyema versus lung abscess

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    Figure 1: split pleura sign of empyema
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    Case 2: empyema
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    Case 1: lung abscess
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