Early symptoms of mesothelioma are difficult to identify and therefore often overlooked. Pleural mesothelioma symptoms may first appear as shortness of breath, chest pains or persistent cough or a change in cough pattern. Some patients however, may show no symptoms at all. Peritoneal mesothelioma symptoms include pain or swelling in the abdomen, nausea, weight loss, bowel obstruction, anemia or swollen feet. Malignant mesothelioma is a cancerous tumor of the pleura (lining of the lung and chest cavity) or peritoneum (lining of the abdomen) that is almost always caused by sustained exposure to asbestos.

Malignant mesothelioma is a diffuse tumor that affects men more frequently than women. Sustained exposure to asbestos is the predominant risk factor. However, smoking dramatically increases risk amongst the asbestos-exposed. The latent period between asbestos exposure and onset of symptoms can be 20 to 50 years or even longer. The median age of diagnosis is 60. The tumor can spread rapidly to involve the pericardium (sac around the heart), mediastinum, and opposite pleura. Progressive pain and shortness of breath can occur. The tumor is usually associated with a pleural effusion.