Description: Mesotheliomas of the pleural cavity are relatively rare tumors. Generally, two types of pleural tumors can be referred to as mesotheliomas. The less common is the solitary (or localized) fibrous tumor of the pleura, previously known as "benign mesothelioma." This slow-growing, commonly benign, well-circumscribed tumor is pedunculated on a pleural-based pedicle and often is cured by resection. The tumor appears to originate from submesothelial rather than mesothelial or epithelial cells.