Pleural mesothelioma is the most common form of the cancer, accounting for roughly 75 percent of all cases. This type of mesothelioma develops in the lining of the lung cavity, known as the pleura, and is often revealed by a CT or MRI of the chest. Obtaining a definitive diagnosis requires a tissue biopsy via needle aspiration or thoracotomy.

Peritoneal mesothelioma is responsible for approximately 10 percent of all cases. Cancer cells grow in the lining of the abdominal cavity, known as the peritoneum, causing symptoms like abdominal pain and swelling, weight loss, and fluid in the abdomen.

Pericardial mesothelioma accounts for about 1 percent of all mesothelioma case and affects the lining of the heart cavity. Pericardial mesothelioma is remarkably rare, but when there is evidence of a pericardial tumor, mesothelioma is the most common cause.

Testicular mesothelioma originates in the tissue of the tunica vaginalis and is extremely rare, with only about 100 cases total reported. Because it is so uncommon, it is difficult to fully understand this type of mesothelioma and the most effective way to treat it.