Diagnosis and treatment of pleural mesothelioma

Pleural mesotheliomas are uncommon tumors. They can be broadly classified as localized and diffuse. The localized form is a non-epithelial neoplasm that occurs as commonly in women as in men and is not related to asbestos exposure. It is usually asymptomatic, and is occasionally associated with paraneoplastic syndromes. Localized mesotheliomas arise more frequently from the visceral than from the parietal or mediastinal pleura. The long-term outcome of these tumors is determined mainly by their clinical presentation, and by whether or not they can be completely resected. Diffuse pleural mesotheliomas are invariably malignant. They are clearly related to asbestos exposure, and are far more common in men than in women. Histologically, they are completely or partially epithelial tumors. Diffuse mesotheliomas present with dyspnea, chest pain, and weight loss and are not associated with paraneoplastic syndromes. Distinguishing malignant mesothelioma from metastatic adenocarcinoma can be difficult and usually requires a large tissue biopsy on which immunohistochemistry and electron microscopy can be performed. The management of diffuse malignant mesothelioma remains controversial. Treatment appears to prolong survival which ranges from 6 to 12 months with supportive care alone. Surgical resection, either with extrapleural pneumonectomy or by pleurectomy/decortications remains the mainstay of treatment because of the relative ineffectiveness of radiation and chemotherapy. Surgical resection alone, however, is inadequate, so most current treatment regimens combine operation with radiation and/or chemotherapy. Even with aggressive multimodality treatment, the median survival currently ranges from 18 to 24 months. A better understanding of prognostic factors, a better staging system, and innovative treatment strategies are desperately needed in this disease.