Localized inflammatory pulmonary disease in subjects occupationally exposed to asbestos

In reviewing pathology materials from patients occupationally exposed to asbestos, we identified eight patients with either localized nodules in their lung or unusual pathologic changes. The chest radiographs of six patients showed isolated parenchymal nodules thought to represent primary neoplasms. In three cases, pathologic examination of these nodules showed intraluminal fibrosis and inflammation of the distal airways, a pattern of change frequently referred to as "bronchiolitis obliterans organizing pneumonitis." In each instance, asbestos bodies were present in association with the fibroinflammatory tissue. In one case, the nodule showed a desquamative interstitial pneumonitis type pattern, and asbestos bodies were present admixed with the alveolar macrophages and occasionally within their cytoplasm. In one case, the nodule was composed of nonspecific inflammation and fibrosis with focal bronchiolitis obliterans and frequent asbestos bodies scattered throughout the area of inflammation and fibrosis, and in another case, necrotizing inflammation association with Aspergillus fungal organisms was identified. Granulomatous inflammation was the dominant pulmonary pathologic change in one patient, and the other patient's lung biopsy specimen showed a diffuse lymphocyte-plasma cell interstitial pneumonitis. The cases reported suggest that asbestos may cause localized lesions in the lung that clinically and radiographically are misinterpreted as cancer and that pathologically show inflammation and fibrosis of the distal airways. In addition, our observations suggest that asbestos may cause granulomatous inflammation, a desquamative interstitial type pneumonitis, and a lymphocytic interstitial pneumonitis type pattern. Our conclusions that asbestos may cause these pathologic changes are supported by case reports in the clinical and pathologic literature, clinicopathologic studies, and by experimental studies.