The term, asbestos, refers to a family of fibrous hydrous minerals that possess unique tensile strength and thermal and chemical stability. Due to the unique thermal stability of asbestos, products containing asbestos have been widely used in a variety of industries, particularly in shipbuilding. The association of exposure to asbestos with pulmonary fibrosis, termed asbestosis, is now well recognized and constitutes one of the major complications of the use of asbestos.
The clinical diagnosis of asbestosis is based on a constellation of nonspecific clinical findings. These findings include the presence of dyspnea and a nonproductive cough, a history of substantial exposure to asbestos, a restrictive pattern on pulmonary function tests, and small linear opacities and pleural plaques on the chest roentgenogram. Out of all of these findings, the greatest significance is often placed on the presence of pleural plaques. Increased public awareness and litigation for personal injury associated with exposure to asbestos has heightened the need for early and accurate diagnostic tests for asbestosis. this
High-resolution computerized tomography provides detailed images of pulmonary parenchyma, and it has therefore been hypothesized that HRCT can be used to detect early asbestosis. The purpose of this study is twofold: (1) to examine the significance of the presence of pleural plaques in the diagnosis of asbestosis; and (2) to examine, through a detailed study of the pulmonary pathologic findings associated with pleural plaques, whether or not there is a morphologic basis for diagnosing asbestosis radiographically.
Materials and Methods
The postmortem files of The Johns Hopkins Hospital were searched for cases in which pleural plaques (Fig 1) were identified at autopsy. Autopsies performed between Jan 1, 1981 and March 31, 1986 were selected for study. Ninety-three autopsies were identified in which pleural plaques were present and in which histologic sections of pulmonary parenchyma were available for study. Ninety-three autopsies of patients matched for age, race, and sex, on whom there was no history of asbestos exposure or pleural plaques, were selected as controls. As with the cases with pleural plaques, all patients used as controls were autopsied at The Johns Hopkins Hospital between Jan 1, 1981 and March 31, 1986.
Figure 1. Pleural plaques, which have been considered to be hallmarks of exposure to asbestos, are composed of relatively acellular hyalinized collagen (hematoxylin-eosin, original magnification x 10).