Localized Inflammatory Pulmonary Disease in Subjects Occupationally Exposed to Asbestos (8)

Lynch et al studied 260 asbestos-exposed individuals by computed tomography (CT) and identified 43 unsuspected pulmonary masses in 27 individuals. These masses included 10 examples of fissural pleural plaques, 3 cases of fibrotic bands, 11 cases of rounded atelectasis, 3 carcinomas, and 16 cases of presumed benign masses. Of these presumed benign masses, 9 were intraparenchymal and 7 were subpleural without features of rounded atelectasis. All of the subpleural masses were “stable” on serial radiographs or CT scans for at least one year, and all were less than 2 cm in diameter. Of the intraparenchymal masses, two were stable for at least one year as determined by chest radiograph and three masses were stable for more than two years. In one patient, no change was identified in three nodules evaluated by CT and chest radiograph over a nine-month period. One 3-cm ill-defined mass resolved without therapy over a six-month period of observation. The subpleural and intraparenchymal masses were not resected, and therefore no comments could be made concerning their pathologic features.
Asbestos dust has been stated not to produce BOOP, and one could question if some other agent cases 1, 2, and 3 were exposed to caused the observed pathologic changes. Auerbach et al have reported that cigarette smoke can cause nodular areas of pulmonary fibrosis, and since cases 1, 2, and 3 were cigarette smokers, their localized disease may have been due to cigarette smoke. The same question could be posed concerning cases 4, 5, and 6, who were also cigarette smokers. A lesion referred to as “respiratory bronchiolitis” characterized by peribronchiolar fibrosis and macrophage accumulation within the lumens of the respiratory bronchioles and adjacent alveoli has been observed relatively frequently in cigarette smokers, although BOOP has been reported not to be induced by cigarette smoke.