Localized pleural malignant mesothelioma.

Pleural malignant mesothelioma (PMM) is a rare tumor and it is commonly seen in the form of multiple nodules or a diffuse tumor. A localized tumor mass in the pleura is extremely rare. Only seven cases have been reported. In this report, we present an additional case of localized PMM and describe the immunohistochemical and flow cytometric findings. A 61-year-old woman, without a history of smoking or asbestos exposure, presented with a severe pain in her right shoulder and arm. Chest radiography showed a solitary mass in the right upper lung field. Computed tomography showed a 5 cm right upper lung mass. Magnetic resonance imaging showed that the mass extended to the wall of the thorax. The patient underwent surgery for total removal of the tumor. Pathology revealed a localized malignant mesothelioma. Immunohistochemical analysis showed that the tumor was strongly and diffusely positive for cytokeratins with high and low molecular weight, and focally positive for vimentin and epithelial membrane antigen (EMA), but it was negative for carcinoembryonic antigen, Factor VIII, alpha-fetoprotein and Leu-M1. Flow cytometry showed an aneuploid DNA content in the tumor. The final diagnosis was localized malignant mesothelioma (epithelial type). The patient showed signs of local recurrence 5 months after surgery, and radiotherapy was given.