How Pseudomyxoma Peritonei Is Diagnosed

Pseudomyxoma peritonei (PMP) can be challenging to diagnose.

Since it’s slow-growing, this condition may not cause symptoms for years. For that reason, the diagnosis of PMP often occurs during tests or treatments intended to diagnose other conditions.

While a physical examination is never enough to diagnose PMP, it can be a helpful starting point to point your healthcare provider in the right direction.

Moreover, if your healthcare provider suspects you have PMP, you will undergo diagnostic tests, such as computed tomography (CT) scan or magnetic resonance imaging (MRI).

You will also need a biopsy (removal of tissue to be analyzed in the pathology lab) to confirm the diagnosis.

This article will discuss the different strategies and technology implemented to diagnose PMP.

Physical Exam

In some instances, you may seek medical attention for PMP symptoms, prompting a physical exam by your healthcare provider. PMP is very rare. It is diagnosed in approximately three or four out of every 1 million people annually.

PMP causes the buildup of mucinous tumor cells in the peritoneum (lining of the abdominal cavity) and pelvis. The tumor cells secrete mucin, a jelly-like substance. This accumulates over time. It causes enlargement of the abdomen—a symptom sometimes referred to as “jelly belly.”

Gastrointestinal distress and abdominal pressure may also occur. Your healthcare provider will palpate your abdomen (examine by touch) to check for swollen areas and other issues. If you have PMP, palpation of your stomach should not cause pain.

PMP symptoms such as abdominal distension and gastrointestinal discomfort usually indicate other, noncancerous conditions. These include irritable bowel syndrome and lactose intolerance.

In males, an inguinal hernia is a common, secondary finding of PMP during a physical examination. Inguinal hernias are caused by a protrusion of part of the intestine through the abdominal wall on either side of the groin.

If you have an inguinal hernia, your healthcare provider may notice or feel a bulge on one side of your pubic bone. This bulge may be more obvious when you’re standing up. Having an inguinal hernia does not mean you have PMP.

Your family history will be asked about as part of your medical history. There is no genetic or hereditary link to PMP, but this could point to other conditions. The most common cause of PMP is appendix cancer (also called appendiceal cancer). If you have had appendix cancer, make sure your healthcare provider is aware of your health history.

Laboratory Tests

You may have routine blood tests drawn, such as a complete blood count (CBC) and a metabolic panel, to check for any abnormalities that could assist in determining the cause of your symptoms.

If a tumor is suspected, your healthcare provider may order blood tests to check for elevated levels of tumor markers (measurable substances that may indicate a tumor is present) in the blood.

A blood test is not enough to make a definitive diagnosis of PMP. However, elevated levels of specific tumor markers may help indicate PMP or other conditions that require additional testing to confirm.

Tumor markers associated with PMP include:

• Carcinoembryonic antigen (CEA): This protein produced by cancer cells may indicate gastrointestinal cancers and other types of cancer.
• CA 125: This tumor marker that's related to mucin production may indicate ovarian cancer, gastrointestinal cancers, and noncancerous conditions, including pelvic inflammatory disease.
• CA 19-9: This protein is produced by cancer cells in people with PMP, other types of bowel cancer, pancreatic cancer, and other conditions.      

Imaging Tests

Your oncologist (cancer specialist) may recommend one or more imaging tests to identify and confirm a PMP diagnosis. These tests are also beneficial for monitoring the progression of this disease. Tests include:

Ultrasound (Sonogram)

Ultrasound uses high-frequency sound waves to create an image of internal organs, which are viewed on a computer screen. An external ultrasound probe will be placed on your abdomen. An internal transvaginal ultrasound may be done to look for PMP tumors on the ovaries.

If the ultrasound findings indicate PMP or other issues, additional imaging tests will likely be needed.

Computed Tomography (CT)

Computed tomography is a painless, noninvasive test. It uses X-ray images to create a three-dimensional picture of your stomach and pelvis. CT scans help your healthcare provider see mucin pockets in the abdominal cavity.

CT scans are done in large, enclosed tubes. For this test, your head will most likely remain outside the tube.

Magnetic Resonance Imaging (MRI)

MRIs use a magnetic field to create images of the tissues in your abdomen, pelvis, and chest. This test is noninvasive and painless.

It is done in a large, enclosed tube that generates very loud noises at various points during testing. It is imperative that you are given earplugs or headphones to cover your ears during an MRI. Some people feel claustrophobic (fear due to an enclosed space) during this test. There will be a panic button to press if you need to halt the procedure temporarily.

In some instances, your healthcare provider may recommend an MRI with contrast. For this test, you will be given a contrast fluid intravenously, right before the MRI procedure. MRI with contrast generates clearer and sharper images than MRI without contrast. Some people experience a slight burning sensation in their arm from the contrast fluid.

Biopsy

A biopsy is needed to definitively diagnose PMP. Types of biopsies that may be performed include:

• Fine needle aspiration biopsy: An ultrasound or CT scan will be done to guide the placement of a needle through the skin. The needle will be used to cut out a tiny piece of tissue. You will be given a local anesthetic to numb the skin, prior to insertion of the needle.
• Laparoscopy (keyhole surgery): This procedure is typically done under general anesthesia. A small incision will be made in your abdomen. A thin tube with a camera on its end, called a laparoscope, will be inserted through the hole. A separate instrument will be used to cut a small piece of tissue for the biopsy.

The removed tissue will be examined under a microscope by a pathologist (a physician specializing in diagnosing disease by laboratory analysis) in a laboratory. The pathologist will look for cancer cells in the tissue.

Differential Diagnosis

Other diseases may present similarly to pseudomyxoma peritonei. These conditions will be ruled out by your healthcare provider:

• Peritoneal carcinomatosis: This is a rare cancer that occurs when abdominal tumors spread to the peritoneum. The main risk factor for this disease is having advanced cancer of the appendix, colon, or other gastric locations.
• Mucinous neoplasm with low risk of recurrence: This rare form of cancer is also referred to as appendiceal mucinous neoplasm with low risk of recurrence. It rarely recurs. No deaths have been reported from this condition.
• Low malignant potential ovarian tumor: This is a single ovarian mass that does not spread cancerous cells to the abdomen
• Mucinous cancers of the ovary, colon, stomach, and gallbladder: These are aggressive tumors that generate mucus in the abdominal cavity. They’re typically more aggressive than the appendiceal tumors that cause PMP.
• Adenocarcinoid (goblet cell carcinoid) of the appendix: This tumor is more aggressive than tumors that cause PMP. Symptoms of this condition mimic acute appendicitis (inflammation of the appendix).
• Appendicitis: This noncancerous condition is earmarked by acute inflammation of the appendix. It may start as slight discomfort around the belly button that leads to intense pain on the right side of the abdomen.
• Mesothelioma: This is a rare form of cancer that may result from asbestos exposure. Mesothelioma usually affects the lungs. However, it can cause mucinous tumors to build up and accumulate in the abdomen.

Summary

Pseudomyxoma peritonei (PMP) is a very rare, slow-growing form of abdominal cancer. You may have this condition for years without any symptoms. Usually, PMP is discovered during tests or treatments for other conditions.

If your healthcare provider suspects PMP, you will have imaging tests done to take a look at your abdominal cavity and pelvis. Blood tests may also be done to check the levels of specific tumor markers in the blood.

A biopsy will be needed to make a definitive diagnosis.

A Word From Verywell

Tests to diagnose PMP are routinely done worldwide every day. You may be concerned about the tests themselves and your potential diagnosis. While you're going through it, remember that getting a diagnosis is a necessary first step to getting the treatments you need to prolong life and get you back to the life you love.