An overview of thoracic actinomycosis: CT features

BACKGROUND: Thoracic actinomycosis is an uncommon, chronic suppurative bacterial infection caused by actinomyces species, especially Actinomyces israelii. METHODS: It is usually seen in immunocompetent patients with respiratory disorders, poor oral hygiene, alcoholism and chronic debilitating diseases. RESULTS: We illustrate the radiological manifestations of thoracic actinomycoses in various involved areas in the thorax. CONCLUSION: Thoracic actinomycosis can be radiologically divided into the parenchymal type, the airway type including bronchiectasis, the endobronchial form, and the mediastinum or chest wall involvement type. TEACHING POINTS: • Important risk factors for thoracic actinomycosis are underlying respiratory disorders such as emphysema and chronic bronchitis. • Different CT patterns can be distinguished in thoracic actinomycosis: parenchymal, bronchiectatic, endobronchial and extrapulmonary. • Typical CT findings in the parenchymal pattern are a central low density within the parenchymal consolidation and adjacent pleural thickening.