[Granulomatous lesions in the lungs of experimental animals]

Granulomatous lesions of the lungs and regional bronchopulmonary lymph nodes in laboratory animals which developed spontaneously but were of epidemic nature are described. Stages of the development of pulmonary lymphoepithelioid granulomas and giant cells, the appearance of caseose-like necrosis, and the development of sclerosis of the nodules are observed. The features of sclerosing of the nodules, localization of histiocytes, macrophages, and collagen fibers are similar to those in a silicotic process in the lungs developing upon administration of Si. Micelium of Aspergilli fungus detected in a number of cases is likely to be the cause of the lesion. The nodular process in its early phases can be differentiated from tuberculosis, pseudotuberculosis, sarcoidosis, and in late stages from nodular silicosis and other granulomatous reactions of hypersensitivity of the delayed type.