What is peritoneal mesothelioma?

More than 2,500 people are diagnosed with mesothelioma in the UK each year.

Mesothelioma is a tumour of the mesothelium. This is a thin lining (membrane) that covers the outer surface of most of our body’s organs. The mesothelium has different names in different parts of the body, In the tummy (abdomen) it’s called the peritoneum.

Mesothelioma that starts in the peritoneum is called peritoneal mesothelioma.

Cancer of the mesothelium is called malignant mesothelioma. However, it’s usually referred to simply as mesothelioma.

The peritoneum has an inner and outer layer. The inner layer covers the abdominal organs and the outer layer lines the abdominal wall. The peritoneum helps protect the organs in the abdomen and keep them in place (shown as the thick line surrounding the abdominal organs in the illustration). When mesothelioma develops in the peritoneum, the layers of the peritoneum thicken. And, fluid may collect between the two layers. This is known as ascites.

Side view of the body showing the peritoneum
Side view of the body showing the peritoneum

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We also have information on pleural mesothelioma.

Cell types of mesothelioma

Mesothelioma can be grouped according to how the cells look under a microscope. There are three main types:

  • epitheloid – this is the most common
  • sarcomatoid (fibrous)
  • mixed (biphasic) – this has both epitheloid and sarcomatoid cells.

Knowing the type of cell involved may give your doctors an idea of how well the disease will respond to treatment.

Back to Understanding peritoneal mesothelioma

What is cancer?

There are more than 200 different kinds of cancer, each with its own name and treatment.