If you’re experiencing desmoid tumor symptoms, your doctor can run tests to rule out other conditions and make a diagnosis. There’s currently no single test that can confirm you have a desmoid tumor. Instead, doctors use imaging tests and tissue samples to look for tumors. They may also run genetic testing to see if you have an inherited condition associated with desmoid tumors.

This article will discuss the different tests used to diagnose desmoid tumors and what they tell your doctor. We’ll also cover the importance of seeking a second opinion when needed and looking for specialized care. Desmoid tumors are complex, and you want to find a doctor who best fits your needs.

History

Your doctor first will ask about your medical history, including how long you’ve had symptoms. Desmoid tumors are usually slow-growing, and some people have symptoms for a long time before seeing a doctor. They’ll ask about your history of trauma, pregnancy, previous surgeries, and family history of cancer.

Physical Exam

Your doctor will continue the diagnostic process by performing a physical exam. During the exam, they’ll ask more about any symptoms you may be experiencing. Be sure to tell them if you have any pain or swelling in a specific area. In some cases, you may even be able to feel a lump or mass under your skin.

Common places for extra-abdominal tumors (tumors outside the abdomen) include the buttocks, shoulders, arms, and legs. Sometimes, people develop intra-abdominal desmoid tumors — desmoid tumors that occur in the tissue around the intestines. Intra-abdominal tumors can cause digestive issues and weight loss. Some people may also experience nausea, cramps, and vomiting.

Using the information you provide, your doctor will take a closer look at your body for any signs of desmoid tumors. They may also ask questions about your medical history. If your doctor finds a lump or wants to investigate your symptoms more, they’ll likely order some imaging tests.

Imaging Tests

Desmoid tumors are noncancerous growths that form in the body’s connective tissues. To see these growths, your doctor can order imaging tests. Examples include magnetic resonance imaging (MRI), computed tomography (CT) scans, and ultrasound.

Magnetic Resonance Imaging

MRI uses powerful magnetic fields to take detailed pictures of your body for measuring tumors. An MRI machine takes images of your body in “slices” — similar to a loaf of bread. When all of the images are put together, it creates a 3D scan.

Doctors use MRIs to look for signs of intra-abdominal and extra-abdominal desmoid tumors. MRIs are also used to see if a desmoid tumor has returned after you’ve had surgery to remove it. In general, doctors prefer MRIs to other imaging methods. This is because desmoid tumors are easier to see when compared to other soft tissues, like muscle.

You’ll need to remove any metal from your body before an MRI. If you have a pacemaker or metal implant, you won’t be able to have an MRI. On the day of your scan, you’ll likely receive an intravenous (into a vein) injection with a special dye called contrast. This dye helps the doctor better see what’s happening inside your body.

Computed Tomography

A CT scan uses X-rays to take detailed images of your soft tissues (fat, muscle, and organs) and bones. The machine collects the images from several different angles. Computer software then uses them to create 3D pictures of your body. Doctors use CT scans to find desmoid tumors or look for another abnormality.

If your doctor thinks you have an intra-abdominal desmoid tumor, they may order a CT scan with contrast. Before your scan, you’ll either have an IV injection or drink a beverage containing contrast medium, which — like the dye you may have injected prior to an MRI — helps your doctor see your body’s tissues in more detail.

Ultrasound

Ultrasound uses sound waves to create pictures of the body’s tissues. If you have a noticeable lump close to the surface of your skin, your doctor may use an ultrasound to take a closer look.

Biopsies

The only way to confirm you have a desmoid tumor is with a biopsy. This test involves removing small tissue samples to look at under a microscope. A pathologist (tissue specialist) is trained to look at cells for abnormalities and make a diagnosis.

There are several types of biopsies used in medicine. Your doctor will choose the best technique based on your tumor’s location. The most common option is a core- needle biopsy. This biopsy uses a wide, hollow needle to take a tissue sample. Fine- needle aspirations use thinner needles but aren’t typically used for desmoid tumors. This is because they can miss the tumor.

Before your biopsy, your doctor may give you sedatives or an anesthetic to make you fall into a sleep-like state. They’ll then numb the area around the tissue they’re going to biopsy. Your imaging test results will help guide what tissues need to be biopsied.

After your biopsy, your doctor will cover the site with a bandage. You’ll be able to go home the same day. You may experience pain and minimal bleeding, so be sure to rest for the remainder of the day. It may take a few days to get your biopsy results back from the pathologist.

Keep in mind, a biopsy result is different from genetic testing.

Genetic Testing

Around 85 percent of spontaneous desmoid tumors are caused by mutations in the CTNNB1 gene. CTNNB1 provides instructions for beta-catenin — a protein that sends growth signals to cells. Too much beta-catenin leads to uncontrolled cell growth and desmoid tumor formation.

Another 5 percent to 10 percent of desmoid tumors are associated with familial adenomatous polyposis (FAP). This inherited condition causes hundreds of polyps (growths) in the intestines. People with FAP are more likely to develop desmoid tumors compared to the general population.

FAP is specifically caused by mutations in the adenomatous polyposis coli (APC) gene. These gene changes are passed down through family members. People with a specific type of FAP — known as Gardner syndrome — are at a higher risk of developing desmoid tumors.

If you’ve been diagnosed with desmoid tumors, your doctor may offer genetic testing to find out if you have mutations in the CTNNB1 or APC genes. The CTNNB1 mutation and APC are mutually exclusive, meaning if you have one, you will not have the other. Looking for these genes involves a simple blood test. APC mutations are found in around 80 percent of people with FAP. Your family members can also have genetic testing done to see if they’re at risk of FAP or desmoid tumors.

Staging

Tumor staging is commonly used with cancer to describe its size, location, and spread. Desmoid tumors aren’t like other types of cancer. Doctors don’t use any official staging system for these tumors. Instead, they base their treatments on your tumor’s size and what (if any) symptoms you’re experiencing.

Getting a Second Opinion

Desmoid tumors are rare, and only 900 to 1,500 new cases are diagnosed every year in the United States. This means that many pathologists have never seen desmoid tumor tissue samples before. The Desmoid Tumor Research Foundation notes that it’s possible to receive a misdiagnosis from a pathologist.

If possible, you can ask your doctor about getting a second opinion from a soft tissue pathologist. These doctors specialize in diagnosing sarcomas or cancers that affect the soft tissues and bones. Desmoid tumor samples require specific tests for an accurate diagnosis, and it’s best if a soft tissue pathologist performs them.

After your doctor confirms you have a desmoid tumor, it’s important to find a sarcoma specialist. They’ll have all the latest information on which treatment options are best suited for you. Many sarcoma specialists work together in teams with other oncologists who focus on surgery, radiation, and medical treatments.

Talk With Others Who Understand

MyDesmoidTumorTeam is the social network for people with desmoid tumors and their loved ones. On MyDesmoidTumorTeam, members come together to ask questions, give advice, and share their stories with others who understand life with desmoid tumors.

Are you living with a desmoid tumor? What tests did you have to reach your diagnosis? Share your experience in the comments below, or start a conversation by posting on your Activities page.