[Pulmonary actinomycosis--diagnosis and therapy based on past reports of actinomycosis].

A 57-year-old man who complained of bloody sputum was admitted to the hospital because of a spherical mass on a chest X-ray film. Despite a detailed examination, no definitive diagnosis was obtained, and a left lower lobectomy was done. Histopathologic examination of tissue from the resected lobe revealed sulfur granules and branching filamentous bacteria, and therefore pulmonary actinomycosis was diagnosed. Examination of reports published in Japan in the last five years suggested a slight increase in the frequency of diagnosis before treatment of actinomycosis and a slight decrease in the frequency of surgical treatment. However, these changes are not surprising because the frequency of surgical treatment is 58%. These findings suggest that pulmonary actinomycosis should be included in the differential diagnosis of a mass on a chest X-ray film.