Primary pulmonary botryomycosis: a bacterial lung infection mimicking lung cancer.

Primary pulmonary botryomycosis, or bacterial pseudomycosis, is an unusual bacterial infection characterised by the formation of eosinophilic granules that resemble those of Actinomyces species infection. The diagnosis of botryomycosis is based on culture of the granules revealing gram-positive cocci or gram-negative bacilli. The bacterial pathogen most frequently found is Staphylococcus aureus. The pathobiology remains unknown. Pulmonary botryomycosis can resemble actinomycosis, tuberculosis or invasive carcinoma. Definitive treatment requires a combination of both surgical debridement and long-term antimicrobial therapy. We present a case of primary pulmonary botryomycosis in an immunocompetent patient.