Pseudomyxoma peritonei

Pseudomyxoma peritonei is a rare disease of the abdominal or peritoneal cavity. The majority of cases result from a ruptured mucus-secreting adenoma (tumour) of the appendix. More rarely, the condition arises in other parts of the bowel; in the ovary in women; and in rare cases, in other organs such as the bladder. 

The disease results in the presence of a large amount of mucinous fluid with the consistency of jelly in the abdominal cavity, and is often commonly referred to as 'Jelly Belly'. The mucus is produced by cells that have spread and grown on the peritoneum which lines the abdominal cavity. 

Usually, malignant (harmful) tumours spread via the lymphatic system to the lymph nodes, and by the blood vessels (known as vascular spread), to reach the liver, lungs, brain and other tissues.  Pseudomyxoma peritonei is often referred to as being a 'borderline malignant' condition as it spreads only within the abdominal cavity in the majority of cases and does not spread via the lymphatics or the blood stream.

However, it is not benign (harmless), as it will continue to grow and will eventually take over the peritoneal (abdominal) cavity. If left untreated, it will cause compression of the abdominal organs, making normal nutrition no longer possible.  The complications of malnutrition (predominantly infection such as pneumonia), and complications following surgical treatment of the disease are common.

Pseudomyxoma peritonei of appendix origin

Pseudomyxoma peritonei that starts in the appendix is said to have an incidence of around three to four per million per year. Common characteristics are an increase in waist size/ swelling of the abdomen (tummy); mucus in a hernia sac; appendicitis; or ovarian cancer in women.

Occasionally, it is found incidentally during a laparoscopy (explorative keyhole surgery of the abdomen) when the surgeon is investigating a patient’s symptoms in order to make a diagnosis.

It is thought that the mucus-secreting adenoma bursts, releasing harmful cells into the peritoneal cavity, which become attached to the peritoneum. The cells release mucus, which produces mucinous ascites (fluid and jelly). The main concentration of cells follow the flow of peritoneal fluid normally found in that area, and tend to accumulate at particular sites within the abdominal cavity.

Mucinous adenocarcinoma

There is a wide spectrum of disease varying from low grade at one end of the spectrum to high grade at the other.

Thus some patients we see have mucinous ascites (fluid and jelly) which suggests patients who have Pseudomyxoma Peritonei of appendiceal origin turn out to have mucinous adenocarcinoma. This is a more aggressive form of disease. It is commonly confused with ovarian cancer in women. A small ruptured tumour of the appendix can result in very large ovarian tumours.

Colorectal Peritoneal Metastases (CPM) occurs when cancer cells from the main colorectal tumour escape into the abdomen, lodging between the lining (the peritoneum) and the other organs or tissues that are contained there. When this happens, they can either be reabsorbed into the lymph system, becoming caught up in the lymph nodes, or they can become embedded and start to grow on the outside of other organs in the abdomen or pelvis.


Mesothelioma in the peritoneum is called peritoneal mesothelioma.  The peritoneum is the lining of the abdomen.  It helps to protect the contents of the abdomen and keep them in place. You may have been diagnosed with peritoneal mesothelioma after investigating symptoms of abdominal pain, increasing abdominal distension (swelling or bloating), weight loss, constipation, diarrhoea. If the abdomen is uncomfortable and swollen, fluid may have collected there.  A small drain can be used to drain the fluid to provide relief.

There is a strong link with asbestos exposure and pleural (lung) mesothelioma, although it is less well defined in peritoneal mesothelioma.

Your doctor will explain your condition, what type of mesothelioma you have and the proposed treatment to you in detail.  Chemotherapy for mesothelioma will not cure the cancer but it can help to improve symptoms and for some people delay the progression of the disease.  Occasionally surgery for peritoneal mesothelioma can be performed.  The aim of the surgery is to remove the disease using a cytoreductive and HIPEC technique.  As with other cancers, surgery depends on a number of factors including general fitness, other illnesses and how advanced the disease is.


Useful information

Mesothelioma UK

A national peritoneal mesothelioma multi-disciplinary team (NPMMDT) is coordinated monthly at Basingstoke Hospital.  Please contact Samantha Westbrook ( or NMDT email ( for information about how cases can be referred and reviewed.