Pseudomyxoma Peritonei: Causes, Symptoms, and Treatment
Medically reviewed by Harsha Moole, MD, Internal Medicine. Last reviewed: October 2, 2026.
What kind of doctor treats Pseudomyxoma Peritonei?
A primary care doctor is often the first to notice the problem and order early tests. Treatment is usually led by a surgical oncologist, sometimes at a center that treats rare abdominal tumors. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is pseudomyxoma peritonei?
Pseudomyxoma peritonei is a rare condition in which a jelly-like substance made by abnormal cells builds up inside the belly. The cells usually start in the appendix, a small pouch attached to the large intestine. The buildup can press on organs and cause the belly to swell.
The name means "false jelly tumor of the lining of the abdomen." Abnormal cells spread onto the lining of the abdomen and make thick mucus that collects in the belly and can form large masses. It grows slowly, and many people have it for years before noticing anything wrong.
Symptoms
Early on, many people have no symptoms. As mucus builds up, the belly may swell and look bigger, sometimes called "jelly belly." Other symptoms can include belly pain, a feeling of fullness, changes in bowel habits, and tiredness.
Causes and who gets it
The cause is usually abnormal cells in the appendix that make mucus and spread inside the belly. It is not known to be caused by diet, lifestyle, or anything a person did. It affects roughly one or two people per million each year, most often adults.
How doctors diagnose it
Doctors often find it during scans or surgery done for another reason. Imaging tests like CT or MRI can show mucus clumps and swelling in the belly. Blood tests and a biopsy, where a small tissue sample is examined, help confirm the diagnosis.
Treatment
The main treatment is surgery to remove the visible disease and the organ where it started, often the appendix. This may be combined with heated chemotherapy placed directly into the belly during surgery. Some patients need regular scans afterward, since the condition can come back.
When to see a doctor
See a doctor if you have ongoing belly swelling, belly pain, or changes in bowel habits that do not go away. These symptoms usually have more common causes, but they should be checked.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance; a concierge doctor usually charges more and often works alongside insurance. Either type can order scans and blood tests, track symptoms over time, and give longer visits to explain results. When the diagnosis is confirmed or strongly suspected, they would refer you to a surgical oncologist, since the surgery is complex.
Common questions
Is pseudomyxoma peritonei cancer?
It is usually considered a borderline or low-grade cancer. It grows slowly and rarely spreads to distant parts of the body, but it can cause serious problems in the belly and needs treatment.
Can it be cured?
Surgery with heated chemotherapy can remove all visible disease in some patients and control it for years. Results differ, and the condition can come back, so regular follow-up helps doctors find any return early.
Why does my belly look bigger?
The mucus made by the abnormal cells slowly fills the belly and makes it swell, sometimes called "jelly belly." Many other conditions can also cause belly swelling, so tests are needed to find the cause.
How rare is it?
It is very rare, affecting roughly one or two people per million each year. Because it is so uncommon, many patients travel to specialty centers for surgery.
Sources
- NIH Genetic and Rare Diseases Information Center - Pseudomyxoma peritonei
- National Organization for Rare Disorders (NORD) - Pseudomyxoma Peritonei
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
