The mesothelium makes a lubricating fluid that helps protect the organs as well as allowing them to move around. For example, this fluid makes it easier for the lungs to move inside the chest when you breathe.
The mesothelium is called the pleura in the chest area. Mesothelioma in the chest is called pleural mesothelioma. This is the most common type of mesothelioma.
The mesothelium is called the peritoneum in the abdomen. This mesothelioma is called peritoneal mesothelioma. This is a less common type of mesothelioma.
Occasionally, mesothelioma starts in the membrane around the heart or the reproductive organs. It forms growths shaped like small pieces of cauliflower. They grow and spread gradually to surrounding areas. A person may develop mesothelioma in more than one place but this is rare.
Tumours developing in the mesothelium can be non-cancerous (benign) or cancerous (malignant). Benign tumours can usually be taken out with surgery and there are no further problems. This site only discusses malignant mesothelioma and mainly those in the chest and abdomen.
Mesothelioma can also be divided into another three types according to how the cells look under a microscope:
- epithelioid: around 60 out of every 100 cases of mesothelioma are this type; people with this type generally have a better prognosis (outcome) than those with other types
- sarcomatoid (fibrous): these make up about 15 out of every 100 cases
- Mesothelioma mixed (biphasic): this means the mesothelioma is made up of both epithelioid and sarcomatoid cells. These make up about 25 out of every 100 cases.
Mesothelioma in the chest (pleural mesothelioma)
Pleural mesothelioma starts in the pleura. The pleura is the two layers of thin membrane that surround the lungs and line the chest wall. The inner layer is attached to the lungs and the outer layer lines the chest wall and diaphragm. Between the two layers is the pleural cavity. This cavity is almost empty. The two layers of pleura slide against each other. They're moist so that lungs can move smoothly against the chest wall as you breathe.
Sometimes mesothelioma can spread into the area around the heart (pericardium)
