Pleural Plaques
Pleural plaques are deposits of hyalinized collagen fibers in the parietal pleura. They are indicative of asbestos exposure and typically become visible twenty or more years after the inhalation of asbestos fibers, although latency periods of less than 10 years have been observed [1-3]. Pleural plaques are presumed to be the result of pleural inflammation caused by asbestos fibers that are transported to the pleural surface along lymphatic channels and/or direct penetration [4,5]. The former may explain why pleural plaques tend to be located near the stomata where asbestos fibers are resorbed by lymphatic flow (ie, Kampmeier's foci) [6]. (See "Asbestos-related pleuropulmonary disease".) Pleural plaques preferentially involve the parietal pleura adjacent to ribs, particularly the sixth through ninth ribs. They are also common along the diaphragmatic pleura. Pleural plaques are less extensive in the intercostal spaces, only rarely occur in the visceral pleura, and are co...