Pleural plaques

Abstract

Hyaline plaques of the parietal pleura, with their characteristic distribution, should be distinguished from diffuse fibrous thickening of the parietal and visceral pleura. A strong correlation exists between plaque formation and exposure to asbestos dust of all types, but an immediate cause and effect relationship has not been established. A latent interval of 20 years between first exposure and evidence of plaque formation is usual; but the prevalence of plaques is more dependent on the age of the patient than on the total dust exposure. Those environmentally exposed from birth develop plaques at an earlier age than those occupationally exposed. Despite radiological advances in the identification of hyaline plaques, calcification remains the most reliable marker for group studies. The pathogenesis of pleural plaques is unknown, but investigation of the transportation of asbestos fibers to selected sites within the body, and immunological studies, would seem to be useful projects for the future.