EMPYEMA NECCESITANS
The axial CT scan examination of the lower chest done without the use of intravenous contrast shows a loculated left pleural effusion with air demonstrated within its confines which indicate an infected pleural space or the presence of a bronchopleural fistula. The arrow points to an area where there is communication between the pleural effusion and the extrapleural space, notably in this case the musculature of the lateral chest wall. This is radiologically compatible with a fistula communication between the possibly infected pleural fluid and the extrapleural space and represents an empyema neccesitans.