Actinomycosis and other bronchopulmonary infections with bacterial granules

Pulmonary infections with formation of bacterial granules are rare. We reviewed the clinical and pathologic data from 18 cases diagnosed using surgical specimens in our department during the last 10 years. Three clinicopathologic forms were observed: endobronchial infections complicating tuberculous sequelae or bronchiectases (n = 7), tumor-like lesions (n = 8), and diffuse pneumonia (n = 3). The two latter forms contrasted with the former by a male predominance, association with general debilitating conditions and inflammatory syndrome, and pathologically by smaller granules often located in parenchymal abscesses or excavations. The pathologic examination of the bacteria forming the granules permitted the diagnoses of actinomycosis (n = 10), botryomycosis (n = 7), or nocardiosis (n = 1). The latter case corresponded to an endobronchial infection. Both actinomycosis and botryomycosis were encountered in every clinicopathologic form. At present, pulmonary actinomycosis and related infections rarely seems to present with chest wall invasion. On the contrary, purely endobronchial forms represented a large proportion of our cases. Cultures are often difficult and the clinical appearance is not specific. However, pathologic examination with special stains must indicate the type of involved microorganism.