Mesothelioma in the abdomen

Mesothelioma in Your abdominal cavity (the bit below your diaphragm) and bowel are also covered by a lining. Like your chest lining, it has two layers. The inner layer covers the organs in your abdomen (your stomach, etc), and the outer layer lines the wall of your abdomen. A tumour can start within this lining. It causes the lining around the organs in your abdomen to thicken. Lots of fluid can also be produced, which causes swelling of the abdomen.