Pseudomyxoma peritonei (PMP)

Pseudomyxoma peritonei (PMP) usually begins as a slow-growing tumour in the appendix, called a Low-Grade Mucinous Appendiceal Neoplasm (LAMN). Rarely, PMP starts in other parts of the bowel, ovary or bladder.

Over time, the tumour produces a jelly-like substance called mucin. This can cause the appendix to swell up like a balloon. The tumour can then break through the wall of the appendix and spread tumour cells into the lining of the tummy (the peritoneum).

The tumour cells and mucin build up in the lining of the tummy, putting pressure on the bowel and causing symptoms. It can be many years before symptoms become obvious. Unlike other cancers, PMP rarely spreads via the lymphatic system or the bloodstream. It usually remains inside the tummy, spreading along its internal surfaces.

Symptoms of pseudomyxoma peritonei

Most people don't have any symptoms for a long time. When symptoms occur, they may include:

  • slow increase in waist size
  • hernia (a swelling on the abdomen)
  • loss of appetite
  • unexplained weight gain
  • abdominal or pelvic pain
  • changes in bowel habits
  • appendicitis.

Most people with these symptoms won't have PMP, but it's important to have any symptoms checked by your doctor.

At The Christie, the colorectal and peritoneal oncology centre treats PMP.

Last updated: March 2023