Mesothelioma is a rare and aggressive cancer. The cancer develops in the mesothelium, a protective membrane that lines three body cavities: the thoracic cavity (pleura), abdominal cavity (peritoneum) and the heart sac (pericardium). In the case of testicular mesothelioma, the cancer develops in the tunica vaginalis, the membrane surrounding the testicles.
Approximately 2,000 to 3,000 Americans are diagnosed with mesothelioma annually.