Pleural plaques as risk indicators for malignant pleural mesothelioma: a necropsy-based study

Pleural plaque is recognized as a reliable marker of previous exposure to asbestos. However, it is controversial whether pleural plaque is a risk indicator for asbestos-related malignancies. In the present study, the thoracic cavities were examined for pleural plaques in 3,005 necropsies performed at the Monfalcone Hospital in people aged 15 years or older. Plaques were classified into three classes: 1, small (plaques measuring 1-4 cm in major diameter); 3, large (plaques involving a major part of a hemithorax); and 2, moderate (intermediate conditions). The prevalences of pleural plaques were 70.9% among men, and 24.0% among women. The prevalences of plaques (total plaques, various classes) among subjects with pleural mesothelioma were compared with those observed in the remaining cases. The series included 92 subjects with malignant pleural mesothelioma (82 men and 10 women). Mesothelioma cases showed higher prevalences of total plaques as well as higher prevalences of classes 1, 2, and 3, when compared with controls. These differences reached the statistical significance for total plaques, and classes 2, 3. The present data are consistent with the idea that pleural plaque is a risk indicator for pleural mesothelioma.