Abstract
A 70-year-old male was admitted for a further examination of an abnormal shadow in the chest roentgenogram, detected during an annual physical examination. Chest roentgenogram showed a bulky shadow on the left hilum extending to the anterior mediastinum. The mass, surrounded by a fatty plate, was located at the anterior mediastinum by computed tomography scans. Magnetic resonance imaging showed that the mass shadow was not connected with lung parenchymal tissue or the cardiovascular system. Moreover, the mass had little fat component shown by T1-weighted images and the intensity, by T2-weighted images, was between that of muscle and that of fat. All of these findings indicated the mass had feature compatible with low grade malignancies. A presumptive diagnosis of mediastinal tumor, especially thymoma was made by these clinical data. Resection of the tumor which was pedunculated and originated from the visceral pleura (S3) was performed. The pathological diagnosis of the resected specimen was benign localized mesothelioma. Benign localized mesothelioma has almost no charactristic clinical symptoms, and shows few diagnostic features on convertional roentgenograms. A case of localized mesothelioma examined by magnetic resonance imaging, in addition to convertional chest X-ray examination and CT scan, was reported.
