Actinomyces in the mediastinum. Surprise is key in all art

Actinomycosis is an unusual chronic granulomatous infectious disease. They are commensals in various sites of the human body but with little pathogenicity. Actinomyces israelii is the most prevalent species but more than 30 species have been described. Infection of the lower respiratory tract is unusual, the involvement of mediastinum being even rarer.

A 63-year-old man, previously healthy and living in a rural area, presented with a 5-month history of hemoptysis, pleuritic pain, weight loss, and night sweats. Community-acquired pneumonia with a mediastinal mass was documented, for which he received antibiotic management. Thoracoscopy was carried out for diagnosis and resection of the mediastinal mass due to inconclusive findings in the percutaneous biopsy. Pathology reported the presence of filamentous Gram-positive bacteria visible in Grocott staining. Due to the pathology findings, and the fact that no other infectious agents were identified, a diagnosis of actinomycosis was established. Treatment with oral amoxicillin 1g TID for 6 months was initiated.

As far as we are aware, we present the sixth case of mediastinal actinomycosis. We present this case to bring attention to this rare but clinically relevant presentation to be considered as a differential diagnosis of mediastinal masses and to emphasize the need for specific anaerobic cultures to improve the diagnostic yield.