Snapshot A 75-year-old man presents to his primary care physician with complaint of feeling excessive fatigue in the past few months. He notices that he feels a tightness in his chest and shortness of breath as he goes about his day, though the discomfort is not exacerbated by deep breathing. He has lost 20 pounds in the past half year despite maintaining the same diet and having a decreased level of activity due to his fatigue. A chest radiograph is obtained and is shown in the image. Introduction Overview mesothelioma is a malignancy involving mesothelial cells that line the body cavities, including the pleura, peritoneum, pericardium, and testis Epidemiology Incidence ~3,000 cases diagnosed/year in the US Demographics men > women 2/3 cases develop in patients ages 50-70 Risk factors asbestos exposure associated with 80% of cases in US asbestos has been banned since the 1960's but patients develop mesothelioma 20-40 years after asbestos exposure ↑ cases in polluted areas compared with nonpolluted areas cigarette smoking is NOT a risk factor Presentation Symptoms progressive dyspnea non-pleuritic chest wall pain fever fatigue weight loss night sweats Physical exam pleural effusion noted upon percussion and auscultation Imaging Chest radiograph findings in malignant pleural mesothelioma obliteration of the diaphragm nodular thickening of the pleura pleural effusion present in > 50% of patients CT or MRI of chest used in the diagnosis of mesothelioma identify pleural abnormalities and extent of disease Studies Thoracentesis performed if pleural effusion is present Pleural biopsy may appear as 1 of 3 histologic subtypes epithelioid tumor cells resemble normal mesothelial cells that form a tubulopapillary or trabecular pattern sarcomatoid composed of tightly packed spindle cells biphasic (mixed) composed of both epithelioid and sarcomatoid components Differential Non-small cell lung cancer distinguishing factor tumor develops in the lung itself (versus pleural lining) Small cell lung cancer distinguishing factor tumor develops in the lung itself (versus pleural lining) Treatment Medical chemotherapy for management of malignant mesothelioma cisplatin pemetrexed gemcitabine radiation may provide palliation of chest pain and chest wall metastasis Surgical tumor resection may be an option if the disease is confined to the pleural space Prognosis Median survival for malignant mesothelioma is 11 months almost always fatal