[X-ray computed tomographic and radiographic aspects of thoracic actinomycosis]

The aim of this study was to evaluate chest radiographs and computed tomography (CT) in patients with thoracic actinomycosis.

Chest radiographs and CT scans of 9 patients with proved thoracic actinomycosis were reviewed. CT scans were performed after intravenous contrast administration.

Airspace consolidation was present in the upper lobes in 6 patients and in the lower lobes in 3. Cavitations not apparent on the radiographs were seen on CT s in 2 cases. Mediastinal lymphadenopathies were seen on CT s in 2 cases, in one the infection extended through the mediastinal pleura into the mediastinum. Pleural thickening adjacent to the airspace consolidation was identified in 6 cases. Chest wall invasion occurred in 4 cases with a wavy periostal reaction involving ribs adjacent to the site of parenchymal involvement in 3 cases. Extension into the abdomen through the diaphragm was seen in one case.

In humans, actinomycosis involves the thorax in 15% of the cases. Thoracic and pulmonary parenchymal involvement is usually secondary to aspiration of colonized material from the oropharynx in patients with poor oral hygiene. There is a basilar predominance of the disease, but some studies have reported apical predominance. The pulmonary infection leads to an airspace consolidation mainly in the lung periphery. The infection may extend across fissures and through the pleura. Chest wall and bone invasion are not uncommon. A wavy periosteal reaction involving ribs is said to be highly suggestive of pulmonary actinomycosis.

Thoracic actinomycosis is characterized by airspace consolidation with adjacent pleural thickening. Chest wall invasion with a wavy periosteal reaction is highly suggestive.