Necrotizing aspiration pneumonia.

Infectious disease is the most common etiology of a cavitary lung process, which can occur with necrotizing pneumonia, lung abscess and septic pulmonary embolism. Other infectious causes of pulmonary cavitation include cavitating fungal or mycobacterial granulomas and superinfection of preexisting spaces. Noninfectious causes of cavitation that should be considered in the differential diagnosis are infarction from thromboembolic disease or vasculitis, necrotic primary or metastatic tumor, rheumatoid nodules and air-filled congenital cysts. The clinical history combined with radiographic features can be helpful in diagnosing the underlying cause of cavitation.