The pathology of parietal pleural plaques.

The incidence, morbid anatomy, histology, and relationship of hyaline pleural plaques to exposure to asbestos has been studied. Plaques were found in 12.3% of 334 hospital necropsies (in an urban population in Glasgow, 41 cases). In 85.3% (35 cases) asbestos bodies were found in the lungs. There is evidence of a dose-response relationship between the number of asbestos bodies found in the lungs and the presence of pleural plaques. The selective distribution of plaques within the pleural cavities suggests that mechanical factors play a part in their localization. Histological examination contributed little to understanding the mechanism of plaque formation; that asbestos bodies have been detected in only a few cases suggest that their presence in the parietal pleura is not essential to plaque formation. The suggested mechanisms of plaque formation are discussed.