What is mesothelioma?

The mesothelium has different names in different parts of the body:

• in the chest it’s called the pleura
• in the abdomen it’s called the peritoneum
• the membrane surrounding the heart is called the pericardium.

A cancer of the mesothelium is called a malignant mesothelioma. However, it’s usually referred to simply as mesothelioma. There are other tumours of the mesothelium, such as adenomatoid tumours, benign cystic mesotheliomas and solitary fibrous tumours of the pleura. Our cancer support specialists| can give you information about these. This section is about malignant mesothelioma.

There are two main types of malignant mesothelioma:

• Pleural mesothelioma
• Peritoneal mesothelioma

Pleural mesothelioma Back to top

The pleura is the outer lining of the lung. It has two layers; the inner (visceral) layer, which is next to the lung, and the outer (parietal) layer, which lines the chest wall. The two layers of the pleura are usually in contact and slide over each other as we breathe. The layers produce fluid, which allows them to move smoothly over each other.

When mesothelioma develops in the pleura (pleural mesothelioma), the delicate linings thicken and may press inwards on the lung. Fluid may also collect between the two layers of the pleura: this is known as a pleural effusion|. Around 3 out of 4 of cases of mesothelioma develop in the pleura.

 

Peritoneal mesothelioma Back to top

The outer lining of the abdomen is known as the peritoneum. It also has two layers: the inner (visceral) layer, which is next to the abdominal organs, and the outer (parietal) layer, which lines the abdominal wall. Mesothelioma in the peritoneum is called peritoneal mesothelioma. It causes thickening of the linings surrounding the abdominal organs and a collection of fluid in the abdomen. The collection of fluid is called ascites| and causes swelling of the abdomen. Around 1 in 4 cases of mesothelioma develop in the peritoneum.

 

 

 Very rarely, a mesothelioma may develop in the outer lining of the heart (pericardial mesothelioma) or in the outer lining of the testes (testicular mesothelioma).

 

Cell types of mesothelioma Back to top

Mesothelioma can be grouped according to how the cells look under a microscope.

 There are 3 main types:

• epithelial – this is the most common
• sarcomatoid (fibrous)
• mixed (biphasic) – these have both epithelial and sarcomatoid cells.

The treatment| is the same for the different types of mesothelioma. Knowing the type of cell involved may indicate how the disease will respond to treatment.