Pulmonary gangrene: radiological and pathologic correlation

Although frequently referred to as pulmonary abscess or necrotizing pneumonia, pulmonary gangrene is a distinct entity, requiring prompt medical and often surgical management. Radiographically, it begins as a lobar consolidation, usually in the upper lobes, develops lucencies, and coalesces to form a cavity. A "mass within a mass" or air crescent sign may be present. A vasculitis ensues, devitalizing parenchyma that must be drained surgically or expectorated through a patent bronchus. Serious complications of pulmonary gangrene that often lead to death are detected on computed tomography (CT) before these changes are apparent on chest radiographs. Specifically, a narrowed or obliterated bronchus impedes drainage of necrotic parenchyma and thrombosis of large vessels prevents the delivery of antimicrobial therapy. We review the literature and report this case to show the importance of CT in the early detection and management of pulmonary gangrene.