What is empyema necessitatis?
Empyema necessitatis is an uncommon complication of an empyema in which the inflammatory process within the pleural space decompresses and extends into the soft tissues of the chest wall, forming a subcutaneous abscess, which may or may not communicate directly with the skin surface. The most common etiologic factor is tuberculosis, and the most common clinical presentation is a palpable mass in the chest wall, sometimes with a cutaneous fistula. This extension into the chest wall usually is not evident on chest radiographs but may be detected with CT or MRI of the thorax.
