Thoracic actinomycosis: CT findings in eight patients.

The chest radiographs and computed tomographic (CT) scans obtained in eight patients with pathologically proved cases of thoracic actinomycosis were independently reviewed by two observers. All patients were alcoholic men aged 42-62 years. Air-space consolidation, seen on the radiograph and CT scan in each case, was present in the lower lobes in seven patients (88%) and upper lobes in three (38%). Pleural effusion was present in five (62%). Pleural thickening adjacent to the air-space consolidation was identified on the radiograph in four (50%) and CT scan in all eight. Cavitation or central areas of low attenuation not apparent on the radiograph were seen on the CT scan in five cases (62%). Hilar or mediastinal lymphadenopathy was identified on the radiograph in three cases (38%) and on the CT scan in six (75%). Chest-wall invasion occurred in only one case (12%). Thoracic actinomycosis is characterized on CT scans by air-space consolidation with adjacent pleural thickening. CT is superior to radiography in assessing the thoracic manifestations of actinomycosis.