Mesothelioma (malignant)

Definition:

A cancerous tumor of the pleura (lining of the lung and chest cavity) that is almost always caused by previous exposure to asbestos.

Causes, incidence, and risk factors:

Malignant mesothelioma is a diffuse tumor that affects men more frequently than women. Exposure to asbestos is a risk factor, with about 7% of asbestos workers affected. The latent period between exposure to asbestos and onset of symptoms can be 20 to 40 years. The median age of onset of symptoms is 70. The tumor spreads rapidly to involve the pericardium (sac around the heart), mediastinum, and opposite pleura. Progressive pain and shortness of breath occurs. The tumor is usually associated with a pleural effusion. Differentiation of the tumor from other conditions of the pleura can be difficult even with tissue from an open lung biopsy. The incidence is 5 out of 100,000 people.