Actinomyces meyeri presenting as an asymptomatic lung mass

A 55-year-old man was admitted to the hospital for an elective herniorrhaphy. A significant past history of smoking and alcohol abuse was noted. The patient had no other complaints but a routine chest X-ray revealed an isolated left upper lobe mass. Laboratory tests were unrevealing and the impression was that the patient had a carcinoma. The surgical specimen consisted of a lobular mass containing multiple microabscesses. Grains consistent with actinomycosis were seen and the cultures grew out Actinomyces meyeri. There was no other evidence of disease.