Peritoneal Mesothelioma Peritoneal mesothelioma is a rare form of cancer that develops in the lining of the abdomen, known as the peritoneum. It is one of several types of cancer linked to asbestos exposure, representing approximately 20% to 25% of the 3,000 cases of mesothelioma cancer diagnosed each year in the United States. The following information is provided to help you learn more about peritoneal mesothelioma. If you are concerned about mesothelioma, your doctor can evaluate any symptoms you may be experiencing and determine a course of action, if necessary. Peritoneal Mesothelioma Symptoms The peritoneum is a thin serous membrane that protects and supports the organs in the abdomen. It is made up of an outer layer (parietal peritoneum), which is attached to the abdominal wall, and an inner layer (visceral peritoneum), which covers the internal organs. A small space between the two layers contains fluid that allows for movement of organs within the abdomen as they fun...