Pseudomyxoma Peritonei

What is PMP?

PMP (jelly belly) is an abbreviation for Pseudomyxoma Peritonei. Pseudomyxoma Peritonei is a rare condition characterized by the presence of mucin-producing tumors (and the mucin which is a jelly like substance) in the abdominal cavity. There are a number of possible origins of PMP, but the most common source is appendiceal (appendix) cancer. The other sources are colorectal cancer, ovarian cancer.

Is it common?

It is a rare tumour, the lifetime odds of being diagnosed with PMP are about 1 in 1 million. However, it is more common than was once thought – possibly due to prior misdiagnosis or misclassification. Most pathologists see the disease infrequently and may misinterpret cell pathology, resulting in an incorrect diagnosis. Patients would benefit from improved awareness and diagnostic methods in the medical community through earlier detection and treatment of PMP.

What causes PMP?

There are a number of theories about the origins of PMP, but there is no known underlying cause. It is generally accepted that appendix cancer is the most common source of the tumors that cause PMP. Cells from a mucinous tumor in the appendix leak into the abdominal cavity and implant on the peritoneum or other abdominal organs. These tumors replicate and produce a mucinous byproduct that spreads throughout the abdomen.

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Figure 1: Tumor near the tip of the appendix

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Figure 2: The tumor grows in size leading to swelling of the appendix

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Figure 3: The appendix ruptures releasing the mucinous tumor which implants all over the peritoneal cavity

The other common sites of origin of PMP are the ovary, stomach, colon, pancreas and other abdominal organs.

Who can be affected by PMP?

PMP affects men and women almost equally. The age at diagnosis ranges from late teens to late in life, with most individuals diagnosed in their 40′s and 50′s. It is generally thought that there is no genetic (hereditary) link to PMP. Risk factors that might predispose an individual to develop PMP are unknown.

What are the common symptoms?

Many patients lack clearly defined symptoms until the disease has reached a relatively advanced stage. The following are some of the commonly reported symptoms:

  • •    Increased abdominal girth
  • •    Bloating
  • •    Pain/discomfort in the abdominal region—can be a dull ache or sharp pains similar to appendicitis
  • •    Hernia symptoms—PMP is often initially diagnosed as a hernia, especially in men
  • •    In women, symptoms of an ovarian cyst or tumor—PMP is often initially misdiagnosed as ovarian cancer
  • •    Ascites (fluid) buildup in the abdominal cavity

What tests are required for diagnosing PMP?

For many patients, PMP is discovered during an unrelated surgical procedure at which time the surgeon observes the mucinous tumors or “studding” on the peritoneum or abdominal organs. A specialist may be able to diagnose the tumor from certain tell tale signs of the tumor in CT scans and Ultrasonography

The following diagnostic tests are also commonly used in diagnosing PMP:

  • •    CT scan of the chest, abdomen and pelvis.  CT scans have some tell tale signs of pseudomyxoma that can lead to the diagnosis . Whereas this is true in most cases,  CT scans are not perfect pictures, and for some patients visible signs of tumor are not present on a CT scan. CT scans also require the judgment of a radiologist who can interpret the scan to identify the signs of PMP
  • •    Diagnostic laparoscopy. Laparoscopy allows direct inspection of the tumor and enables a biopsy. This helps in determining the extent of disease  and knowing the grade of the tumor which is useful for deciding the course of treatment. Again, proper diagnosis depends upon the surgeon performing the procedure. If PMP is suspected, a specialist in the disease should be brought in to take the proper precautions.
  • •    Blood tests (tumor markers). Some tumor markers in the blood have been shown to be indicative of PMP activity, particularly CEA, CA-125, and CA 19-9. Unfortunately, tumor markers are not accurate or indicators for everyone. Some patients will have no elevation in their tumor markers despite having extensive, aggressive tumor.
  • •    Biopsy: tissue from the mucinous deposits or the primary tumor if seen may be taken to prove the diagnosis before starting treatment. It is also important to know the grade of the tumor. Low grade tumors have a more favourable outcome as compared to high grade tumors.

Does this tumor spread to other organs?

PMP has a tendency to remain confined to the peritoneal cavity for a prolonged period. It keeps growing in size within the peritoneal cavity. It then spreads to the pleural cavity (the space around the lungs).

What happens is the tumor is left untreated?

If left untreated, the tumor will grow in size and produce discomfort due to the bulk itself. It may cause intestinal blockade. It could spread to the pleural cavity and produce difficulty in breathing.

What is the treatment for PMP?

The “standard of care” for the treatment of PMP by PMP specialists is generally a combination therapy that consists of specialized cytroreductive surgery (CRS) to attempt to remove all of the tumors and affected tissues, followed by localized application of heated intraperitoneal chemotherapy (HIPEC).

For many patients this therapy is conducted to increase longevity or to relieve some of the symptoms that affect their quality of life. For other patients this combined therapy carries good odds for long-term survival, with the possibility of completely eliminating the disease.

Can’t any good physician / surgeon treat PMP?

It is highly recommend that PMP patients seek out a specialist who deals with PMP on a regular basis. The key to success is the surgical acumen, if some tumor is left behind, a recurrence is unavoidable.

A team of doctors work on each case, and this team includes a PMP specialist accompanied by another experienced surgeon, a team of anaesthetists, intensive care specialists, medical oncologists, trained nurses, physiotherapists and dieticians.

Are systemic chemotherapy and/or radiation effective treatments for PMP?

There is presently no consensus in the medical community about the use of systemic chemotherapy and/or radiation in treating PMP. Some individuals appear to benefit from systemic chemotherapy while others do not. However, neither chemotherapy nor radiation have proven to be curative for PMP.

Is PMP curable?

For most patients PMP is considered treatable, but not curable. There are, however, a growing number of individuals—primarily those whose disease was detected early and with favorable pathology (low grade tumors)—who have undergone cytoreductive surgery and HIPEC and experienced years of disease-free survival.  It is not uncommon for these patients to survive beyond 15-20 years