CT findings in malignant pleural mesothelioma related to nonoccupational exposure to asbestos and fibrous zeolite (erionite).

Endemic malignant pleural mesothelioma (MPM) in Turkey is related to two mineral fibers, tremolite asbestos and fibrous zeolite (erionite). Thirteen cases of MPM from the Cappadocian area, where the soil is rich in erionite, and 29 cases of MPM, from villages whose occupants have high asbestos exposure, were examined by CT. The CT findings of the two groups of MPM were compared with respect to the configuration of the pleural lesions, stage of disease, fissural involvement, pleural effusion, presence of calcified pleural plaques, and chronic fibrosing pleuritis. In erionite-related MPM the pleural lesions were flat and smooth in 69.1%; in asbestos-related MPM the lesions were nodular in 55.1%. Stage IV disease, calcified pleural plaques, and chronic fibrosing pleuritis were more common in the erionite-related MPM. The rest of the findings were similar in both groups. The early radiological diagnosis of erionite-related MPM may be even more difficult because of the similarity of the pleural lesions to chronic fibrosing pleuritis.