Mesothelioma The disease

Mesotheliomas are cancers that develop from the membranes, called, serous membranes that surround the deep organs.
They can thus develop from:
the membrane surrounding the lungs, pleural mesothelioma
Pericardium, the membrane surrounding the heart Peritoneum, the membrane surrounding the intestines The vaginal membrane surrounding the testicle The epithelium surrounding the ovary.

However over 80% of mesothelioma affect the pleura is a serous (sac) that surrounds the lung, constituting the most common cancer of that organ.