Key Points

• Primary pleural tumors, whether benign or malignant, are rare.
• Approximately 75% of all pleural lesions represent distant metastatic foci of other primary cancers.
• Benign pleural primary tumors, such as the solitary fibrous tumor of the pleura (SFTP), are exceedingly rare.
• The most common malignant pleural primary tumor is malignant pleural mesothelioma (MPM), which carries an overall poor prognosis.
• The treatment approach to benign primary pleural tumors is surgical excision, which is curative with complete (R0) resection.
• A multimodality approach incorporating surgery, systemic therapy, and/or radiotherapy may extend survival in select patients with MPM confined to the ipsilateral pleural cavity.
• Macroscopic complete resection (MCR) is a critical endpoint of surgical resection of MPM.
• Immunotherapeutic and targeted molecular therapies for MPM are currently being explored.

Primary tumors of the pleura are rare. The diagnostic process often reveals the suspicious pleural thickening, pleural effusion, or pleural based mass to be a metastatic focus of another primary cancer, principally lung, breast, or lymphoma. In fact, 75% of suspected pleural tumors are found to be distant metastatic deposits. Occasionally, the diagnosis rests on one of several benign pleural entities, which include solitary fibrous tumor of the pleura (SFTP), lipoma, endothelioma, angioma, pleural cysts, plaques, amyloidosis, or endometriosis, but these benign pleural primaries are extraordinarily rare. By far the most common malignant primary pleural tumor is mesothelioma. Malignant pleural mesothelioma (MPM) is a highly aggressive and usually fatal primary tumor the the pleura. More has been written about this devastating malignancy than about all other pleural entities combined.