Pleural Mesothelioma

DefinitionTop

Pleural mesothelioma is a malignant tumor that arises from the serous cells in the lining of the pleural cavity. The most common cause is exposure to asbestos, with a latency period of ~30 to 40 years from exposure to the development of mesothelioma and with what appears to be a dose-response relationship. The average age of onset of the disease is ~60 years. The disease is 2 to 3 times more common in men, which is attributed to historical differences in exposures.

Clinical FeaturesTop

Most often ≥1 of chest pain (usually severe), weight loss, and dyspnea. Other features include cough and in more advanced stages chest deformation and immobilization on the side of the tumor. The disease is usually aggressive with a predominantly local pattern of spread (chest wall, lung, mediastinum); median survival time is 9 to 17 months following diagnosis. Viscous pleural fluid appearance on thoracocentesis should raise the suspicion of pleural mesothelioma. Thrombosis is very common.

DiagnosisTop

Chest radiography reveals pleural effusion, extensive pleural thickening and nodules, and often infiltration of the interlobular fissures. Chest radiography is insufficient for diagnosis and staging. Computed tomography (CT) provides a much greater resolution and may show the typical radiographic features of a pleural effusion with associated irregular pleural thickening that can involve the mediastinal surface and can often be circumferential with local infiltration of the chest structures. Cytology of the pleural fluid may reveal cancerous cells, however it is commonly falsely negative. Thoracoscopy with pleural biopsy is often required. When thoracoscopy is not possible or contraindicated, ultrasound- or CT-guided biopsy are alternatives. Nearly all pleural mesotheliomas are diffuse. Most malignant mesotheliomas appear as one of the 3 histologic subtypes: epithelioid, sarcomatoid, or biphasic. The epithelioid form is associated with relatively the best prognosis, and the sarcomatoid form, with the worst prognosis. The severity of the disease is determined according to the tumor, node, metastasis (TNM) system.

TreatmentTop

For patients with epithelioid tumors limited to one hemithorax, a detailed multidisciplinary review is indicated to assess whether the disease is amenable to aggressive surgical intervention including extrapulmonary pleuropneumonectomy with diaphragm and pericardial resection or pleurectomy and decortication (lung-sparing surgery), often with complementary radiotherapy. This treatment is possible only in few patients. In advanced stages of mesothelioma, chemotherapy (with or without vascular endothelial growth factor [VEGF] inhibition) and/or immune checkpoint inhibitors can be considered. An important element of palliative treatment is pleurodesis or installation of a tunneled pleural catheter (see Exudative Pleural Effusion Caused by Malignancy). In selected patients who are not eligible for resection, especially in patients with chest pain, palliative radiotherapy is used.