• Malignant mesothelioma is MC tumor of the pleura • In 20% of malignant mesotheliomas, the tumor arises from peritoneum • Exposure to asbestos is the major known risk factor • More common in males, most common after 40 years of age. • Three types: Epithelial, sarcomatous, and biphasic • Epithelial types are associated with a more favorable prognosis Pathophysiology • Physical characteristics of specific fibers (referred to as serpentine or amphibole) have been shown to be important. • Serpentine fibers: Large and curly, not able to travel beyond larger airways. • Straight amphibole fibers: In particular the crocidoliteQ fibers navigate distally into the pulmonary parenchyma, most clearly associated with mesotheliomas. • Latency period between asbestos exposure and the development of mesothelioma is at least 20 years. • Multicentric tumor with multiple pleura-based nodules coalescing to form sheets of tumor (but not bilaterally symmetrical) • Natural history of the disease in untreated patients culminates in death due to local extension. Clinical Features • Most patients present with dyspnea and chest pain. • Over 90% have a pleural effusion. Diagnosis • Results of thoracentesis are diagnostic in <10% of patients. • Chest X-ray: Pleural effusion, generalized pleural thickening and shrunken hemithorax. • Thoracoscopy or open pleural biopsy with special staining of tumor samples is required to differentiate mesotheliomas from adenocarcinomas. Management • No effective therapy • Treatment options: Supportive care only, surgical resection, and multimodality approaches (using a combination of surgery, chemotherapy, and radiation therapy).