Pulmonary botryomycosis on a lung cavity: a rare pulmonary infection mimicking cancer.

Lung botryomycosis is a rare disease. We report what is to our knowledge the first case occurring on a lung cavity. In a 42-year-old man suffering asthenia and cough, a chest radiograph revealed a right upper lobe opacity. Computed tomography scan showed a necrotic mass which was also spiculated. Repeated research for Mycobacterium tuberculosis was negative. The patient underwent a lobectomy. Histological and bacteriological examinations made the diagnosis of botryomycosis, because the cavity presented numerous colonies of pyogenic Fusobacterium nucleatum bacteria. Botryomycosis is a difficult diagnosis that clinically mimics actinomycosis, tuberculosis or cancer. In most cases, surgery is necessary to assess diagnosis and treatment.