Thoracic actinomycosis

OBJECTIVE. Thoracic actinomycosis is a chronic suppurative pulmonary or endobronchial infection caused by Actinomyces israelii, a gram-positive anaerobic organism. We present the CT features of thoracic actinomycosis with histopathologic correlation.

CONCLUSION. The typical CT feature of parenchymal actinomycosis is a chronic segmental air-space consolidation containing necrotic low-attenuation areas with frequent cavity formation. A broncholith can be secondarily infected with Actinomyces organisms, resulting in endobronchial actinomycosis. It usually manifests as a proximal endobronchial calcification associated with distal obstructive pneumonia.

Thoracic actinomycosis is a chronicsuppurative pulmonary or endobronchialinfection caused by Actinomyces species, most frequently Actinomyces israelii, a gram-positive anaerobic saprophytic organism in the oral cavity that historically was thought to be fungus, but now is considered to be a branching filamentous bacterium. Actinomyces infection typically follows aspiration of endogenous organisms of the oropharynx into the lungs in persons with poor oral hygiene or from extension of cervicofacial infections. The clinical manifestations of pulmonary actinomycosis are productive cough, low-grade fever, and bloodtinged sputum. The prognosis is generally goodprovided that the infection is recognized and appropriate antibiotic therapy is instituted. A number of articles have described the CT findings of pulmonary actinomycosis, and there also have been reports of CT findings of endobronchial actinomycosis associated with a foreign body or broncholithiasis. We present the CT features of thoracic actinomycosis, including endobronchial actinomycosis, with histopathologic correlation.