Localized malignant pleural mesothelioma showing a thoracic mass and metastasizing to the stomach.

Malignant mesothelioma typically shows either diffuse tumors or multiple pleura-based nodules. Localized malignant mesothelioma is rare. In this case report, a 70-year-old man with left chest wall tumor underwent tumor resection, and the lesion was pathologically diagnosed as biphasic malignant mesothelioma. Tumor recurrence was detected in the stomach due to vomiting of blood, and also spread to the mediastinal lymph node, and bone 3 months postoperatively. Total gastrectomy was performed and the histopathological diagnosis of metastasis of mesothelioma was made. In the previously reported cases, all of the localized malignant mesothelioma arose in the pleural space and there was no metastasis of localized malignant mesothelioma to the stomach. In the present case, gross and histological examinations were performed for both the primary lesion and gastric metastatic tumor. Though it was very difficult to distinguish mesothelioma from sarcoma and other chest wall tumors, immunochemical staining was able to facilitate making the diagnosis. This case suggests that localized malignant mesothelioma is capable of showing multiple forms and a variety of clinical courses. Localized malignant mesothelioma can arise primarily from the chest wall.