Pericardial mesothelioma develops in the pericardium, a membrane made up of mesothelial cells that surrounds the heart and provides protection and support to this organ. The membrane is composed of two different layers - an outer layer called the parietal layer, and an inner layer known as the visceral layer. The parietal layer is part of a larger membrane that lines the entire chest cavity, while the visceral layer is the pericardial membrane that lines the heart.
