Pulmonary lesions induced by inhaled plutonium in beagles

The histopathologic features of pulmonary fibrosis and bronchiolo-alveolar carcinoma in beagles exposed to aerosols of plutonium oxide were reviewed. A hypothesis of the pathogenesis of radiation pneumonitis induced by inhalation of plutonium oxide was presented; this hypothesis included phagocytosis of plutonium particles, fibrosis responding to the necrosis, and alveolar cell hyperplasia compensating for alveolar cells killed by alpha radiation. Histopathologic features of the epithelial changes suggest a progression from hyperplasia to metaplasia and, finally, to bronchiolo-alveolar carcinoma. The possibility of concurrent radiation-induced lymphopenia contributing to the development of bronchiolo-alveolar carcinoma through a loss of immunologic surveillance was discussed