The second most common form of the disease, peritoneal mesothelioma forms in the abdomen, more specifically, the mesothelial cells that create a membranous layer known as the peritoneum.

The peritoneum is made up of two layers--the visceral layer and the parietal layer. The visceral layer surrounds the organs in the abdomen, while the parietal layer covers the abdominal cavity. Together these layers offer protection and support for the abdominal cavity and its organs. 

Peritoneal mesothelioma is caused by asbestos exposure; however, it is not known exactly how asbestos fibers become stuck in the peritoneal lining. One theory suggests that after asbestos fibers are broken into smaller pieces in the lungs, they are carried into the bloodstream and then become stuck in the peritoneum. A more probable theory proposes that asbestos fibers were ingested through food or drink. Many asbestos facilities were constantly covered in clouds of asbestos fibers. These fibers could have landed on the worker's food. Also, because asbestos often attached to a worker's clothing, the fibers could have been brought home into the kitchen and ingested. Once these fibers become stuck in the peritoneum, the constant inflammation can cause cancerous tumors.

Peritoneal mesothelioma symptoms usually do not manifest until 20 to 50 years after the asbestos exposure. The majority of peritoneal mesothelioma symptoms stem from membrane thickening, tumors and a build-up of fluid. Some common symptoms of this asbestos-related disease include:

• Abdominal pain or swelling
• Lumps under the skin on the abdomen
• Changes in bowel movements
• Night sweats
• Fever
• Anemia
• Nausea/vomiting
• Fatigue