Localized pleural mesothelioma.

The clinical and radiological presentation of five anatomo-pathologically proven cases of localized pleural mesothelioma are described. In all patients conventional chest films and CT scans were performed. Two patients had also an MR examination. On conventional chest films all lesions presented as sharply defined homogeneous masses. In most cases there was inhomogeneous contrast enhancement on CT. In two cases calcifications and pleural effusion were present. There was no chest wall invasion, nor mediastinal adenopathy. On MR T1-weighted images, the tumor had an intermediate to high signal intensity. In the one case in which T2-weighted sequences were performed, tumor signal intensity increased compared to that on T1-weighted images. In contrast to what is generally found in literature and probably because the series contained rather large masses, most patients had symptoms while the mass was inhomogeneous on CT. Conventional chest films together with CT and MRI are helpful in differentiating this entity from malignant mesothelioma. However, focal areas of malignant degeneration cannot be excluded radiographically.