Pulmonary alveolar proteinosis as a component of massive fibrosis in cases of chronic pneumoconiosis. An autopsy study of 79 cases.

Histopathological analysis of massive fibrosis (MF) in lungs obtained from 79 patients with chronic pneumoconiosis revealed evidence of pulmonary alveolar proteinosis (AP) in a surprisingly high proportion of the cases (73%), suggesting that AP may be a usual constituent of MF in chronic pneumoconiosis. AP is not a specific morphological counterpart responsible for acute silicosis. In order to explain the occurrence of AP in MF, several hypothetical mechanisms are proposed and discussed.