Types of Mesothelioma

About 75% of mesotheliomas start in the chest cavity. They are known as pleural mesotheliomas. Another 10% to 20% begin in the abdomen. These are called peritoneal mesotheliomas. Pericardial mesotheliomas start in the cavity around the heart and are very rare. The covering layer of the testicles is actually an outpouching of peritoneum into the scrotum. Mesotheliomas that affect this covering of the testicles can occur but are quite rare.

It is important not to confuse malignant mesothelioma with benign tumors that also start in the mesothelium. The mesothelium of certain female and male reproductive organs may develop a type of benign tumor called an adenomatoid tumor. In men, this non-cancerous tumor often starts in the epididymis (a small collection of ducts that carry sperm cells out of the testicle). In women, this tumor may begin in the fallopian tubes (tubes that carry eggs from the ovaries to the uterus or womb). Another non-cancerous tumor that may begin in mesothelium near female reproductive organs is called benign cystic mesothelioma.