Pulmonary and hepatic actinomycosis: atypical radiologic findings of an uncommon infection

Abstract

Actinomycosis is an uncommon infection caused by Actinomyces israelii, characterized by clinical and radiological findings that can resemble other inflammatory and neoplastic lesions. In the lung, the pathogen classically causes a chronic pneumonia, which may have associated pleuritis, abscesses and fibrosis. It is estimated in the literature that only 15% of all cases of actinomycosis involve the thorax [1‐ 3]. The causative agent, Actinomyces, usually A. israelii, is non acid-fast, Gram-positive, filamentous bacterium belonging to the same family as Nocardia asteroides. The bacterial species is usually part of the normal flora of the oral cavity. Of particular relevance is the variability of both the radiographic appearance of actinomycosis as well as its clinical presentation. Recognizing this is critical to considering this diagnosis and allows for a specific work-up involving anaerobic cultures and appropriate fluorescent antibody stains. We report a case with unique CT findings of pulmonary and hepatic actinomycosis.