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.
What is peritoneal mesothelioma?
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. It also produces fluid that acts as a lubricant and helps the abdominal organs move smoothly against each other. The peritoneum is formed of mesothelial cells. If these cells grow abnormally, it is called peritoneal mesothelioma.
Peritoneal mesothelioma is much less common than pleural mesothelioma and though the precise figures are unknown, peritoneal mesothelioma probably represents no more than 7-10% of all mesotheliomas.
Like mesothelioma that occurs in the lining of the ribcage (pleural mesothelioma), peritoneal mesothelioma can be caused by exposure to asbestos. Although for peritoneal mesothelioma links with asbestos can be less clear.
Are there different types of peritoneal mesothelioma?
Peritoneal mesothelioma is categorised into two groups: Diffuse malignant peritoneal mesothelioma (DMPM) and low-grade peritoneal mesothelioma (LGPM).
DMPM includes epithelioid, sarcomatoid and biphasic subtypes. Malignant means that the tumour is made of cancer cells that grow abnormally and are likely to spread. The majority of DMPM’s are treated with drug treatments such as chemotherapy or immunotherapy.
LGPM includes multicystic mesothelioma, and well differentiated papillary mesothelial tumour. Low grade cells look more like normal cells and tend to grow and spread more slowly than high grade cancer cells. LGPM does not invade nearby tissues or spread to other areas of the body and they are less aggressive than other types of peritoneal mesothelioma.
How is peritoneal mesothelioma diagnosed?
People who develop peritoneal mesothelioma often have mild, vague symptoms. These can include abdominal pain and sometimes swelling, constipation, diarrhoea, tiredness, loss of appetite and weight loss
Sometimes several tests are needed to confirm the diagnosis. These can include a CT scan, an ultra-sound scan, or a laparoscopy – a keyhole surgical procedure.
How is peritoneal mesothelioma treated?
Treatment options depend on a few factors including general fitness, other illnesses, the subtype of peritoneal mesothelioma and how advanced the disease is. Possible treatments can include immunotherapy, chemotherapy, surgery, surveillance and medication.
Occasionally surgery for peritoneal mesothelioma can be performed. The aim of the surgery is to remove the disease using a cytoreductive and heated intraperitoneal chemotherapy technique. As with other cancers, surgery depends on a number of factors including general fitness, other illnesses and how advanced the disease is.
Specialist review
Due to the rarity of peritoneal mesothelioma it is recommended that people are referred to a specialist team experienced in peritoneal mesothelioma. Experts in the field will carefully review x-rays, scans, surgical findings and biopsy specimens. They will review all this information within a multidisciplinary team (MDT) meeting and provide a specialist opinion and recommendations.
The Peritoneal Malignancy Institute, Hampshire Hospitals NHS Foundation Trust at Basingstoke Hospital hosts a National Peritoneal Mesothelioma MDT and provides a service for a specialised surgical technique for peritoneal malignancy.
Useful information
A National Peritoneal Mesothelioma MDT meeting is coordinated twice a month at Basingstoke Hospital. For information about how cases can be referred and reviewed to the National Peritoneal Mesothelioma MDT please email: pmimesomdt@hhft.nhs.uk
Samantha Westbrook, Peritoneal Mesothelioma Clinical Nurse Specialist: 01256 852822 samantha.westbrook@hhft.nhs.uk
Mesothelioma UK website: Mesothelioma UK
Faheez Mohammed Consultant Colorectal Surgeon and Samantha Westbrook Peritoneal Mesothelioma Clinical Nurse Specialist present their experience of managing peritoneal mesothelioma including diagnosis, treatment with Cytoreductive Surgery and hyperthermic intraperitoneal chemotherapy (HIPEC), the National Peritoneal MDT and the role of our the Peritoneal Specialist Nurse.
