Pleural mesothelioma is a malignant tumor of the pleura, strongly associated with exposure to asbestos on a regular basis (or asbestos).
Asbestos fibers are extremely thin and penetrate through the respiratory tract. At the level of the pulmonary alveoli, the particles inhaled trigger an immune response: macrophages engulf the foreign bodies and release locally these cytokines and growth factors that stimulate an inflammatory reaction. This leads to collagen deposition and, finally, to the interstitial fibrosis (asbestosis).
Asbestos fibers can also exert a direct toxic and mutagenic indirectly for pleura and lung tissue. The time between exposure to asbestos and the onset of mesothelioma can be very long, in the order of a few decades.
Other factors that may predispose to the development of this tumor are some genetic damage, irradiation to the chest and previous lung infections (especially those incurred by the SV40 virus).