OBJECTIVE: Thoracic actinomycosis is a chronic suppurative pulmonary or endobron-chial 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 seg-mental 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.