Empyema necessitans in the setting of pneumonia and parapneumonic effusion.

Empyema necessitans is a rare complication of pleural space infections and occurs when the infected fluid dissects spontaneously into the chest wall from the pleural space. This process may result from bronchopleural extension of a peripheral lung infection. These cases result from inadequate treatment of an empyema and usually occur after a necrotizing pneumonia or pulmonary abscess. We present two cases of empyema thoracic necessitans.