Distinguishing between an empyema and a peripherally located pulmonary abscess is essential.
- abscess is usually round in all projections
- an abscess may form an acute angle with the costal surface / chest wall
- empyema is usually lentiform
- 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
- abscesses have thick irregular walls
- empyema are usually smoother
- angle with pleura
- abscesses usually have an acute angle (claw sign)
- empyema have obtuse angles
- 1. Stark DD, MP Federle, PC Goodman et al. “Differentiating lung abscess and empyema: radiography and computed tomography.” Am. J. Roentgenol. 141, no. 1 (July 1, 1983): 163-167. [Link].