Lung Abscess versus Empyema
Coronal reformatted chest CT images show a lesion in the right upper lobe with internal air-filled cavity, thick irregular wall (green arrowheads) and another lesion in the left lower lung with internal fluid, thin wall (yellow arrowhead) and adjacent compression of the lung tissue (yellow arrows and box). The right upper lobe lesion is an abscess and the left lower lung lesion is an empyema.
Localized suppuration with destruction of lung parenchyma
Round, thick-walled cavity in areas of destroyed lung
Typically irregular wall, irregular luminal margin and exterior surfaces
Usually treated by prolonged antibiotics and postural drainage
Pus in the pleural cavity
"Split pleural" sign: separation of uniformly thickened visceral pleura from parietal pleura
Compression of uninvolved lung
Usually require early tube drainage