Testicular mesothelioma is the rarest form of malignant mesothelioma, a cancer caused by asbestos exposure. To date, less than 100 cases of this type of mesothelioma have been reported.Testicular mesothelioma develops in the membranous lining that surrounds the testicle, the tunica vaginalis, which provides protection and support for the reproductive organ.

Because testicular mesothelioma is extremely rare, very little is known about how it develops. Most researchers theorize there are two possible points of origin for testicular mesothelioma. The tunica vaginalis, the membrane where testicular mesothelioma develops, is composed of mesothelial cells, which are present in most of the body’s membranous linings. The tunica vaginalis is made up of two layers, known as the parietal (outer) and visceral (inner) layers.

Firm white-yellow nodules can be found on the serosal surface of the tunica. The nodules can eventually encase the contents of the scrotum, and cause the tunica vaginalis to thicken.

testicular mesothelioma

While there is currently no theory to explain why asbestos exposure might cause a primary tumor to develop in the testicles, it is understood that once the asbestos fibers are in the body, they can become lodged in organs and cause inflammation or infection that can result in the development of mesothelioma. The fibers cause cancerous cells to divide abnormally, causing buildup of fluid and the development of tumors.

Once cells have become cancerous, they are no longer able to regulate their own cycles of growth and division. A primary tumor that develops in the testicle is formed from cancerous cells that divide without restraint, which causes the thickening of the tunica vaginalis and can eventually lead to the formation of tumors.