Getting a new diagnosis can be scary, especially if it’s a rare disease you’ve never heard of before. If you’ve recently been diagnosed with a desmoid tumor in the hand, arm, thigh, or leg, you may be wondering what to expect next and what you need to know.

Desmoid tumors are not cancerous, but they are serious health conditions that require care from experienced health care providers. This article will cover six important things to know about desmoid tumors in the hand, arm, thigh, or leg.

1. Desmoid Tumors in the Hand, Arm, Thigh, or Leg Are Called Extra-Abdominal Tumors

Desmoid tumors are benign (noncancerous) growths that develop in the body’s soft or connective tissues, such as nerves, ligaments, muscles, and tendons. Although they don’t metastasize (spread) to other parts of the body, desmoid tumors can be locally invasive and cause harm to nearby organs or nerves. You may hear your doctor refer to your desmoid tumor as a deep or aggressive fibromatosis.

Desmoid tumors are rare, affecting about 900 to 1,500 new individuals in the United States every year. Desmoid tumors in the hands, arms, thighs, or legs are classified as extra-abdominal desmoid tumors because they form outside the abdomen (the stomach and other internal organs within the abdominal cavity). It’s common for desmoid tumors to develop in the hands, arms, thighs, and legs.

2. They Can Be Painful and Interfere With Movement, Mobility, and Balance

Desmoid tumor symptoms depend on the tumor’s location in the body. In the early stages, your tumor may not cause any symptoms. Following are some of the most common symptoms reported for desmoid tumors in the extremities (arms and legs).

Painful or Swollen Lump

The most common symptoms of a desmoid tumor in the extremities are swelling and pain. For desmoid tumors in the hand, arm, thigh, or leg, a lump may be more noticeable than one that develops within the abdominal wall. If you notice a pain or slow-growing lump, be sure to tell your health care provider about it.

Difficulty With Movement, Mobility, or Balance

When desmoid tumors form in the hands, arms, thighs, or legs, the tumor can grow large enough to damage the surrounding bones, muscles, and nerves. This may cause difficulty with movement, mobility, or balance. Tumors in the arms and legs are more likely to affect the surrounding joints or nerves, leading to problems with movement.

Pain, Weakness, or Pins-and-Needles Feeling

The nerves that run through your arms and legs are highly sensitive, and added pressure can cause problems with feeling and sensation. For desmoid tumors in the extremities, people often experience pain, weakness, or a “pins-and-needles” feeling.

Fatigue or Insomnia

It’s common for people living with desmoid tumors in the hand, arm, thigh, or leg to report feeling more tired than usual or to have trouble sleeping.

Be sure to speak with your health care team about all of the symptoms you are experiencing. They can discuss with you all the possible options for treating the symptoms of your desmoid tumor.

3. A Biopsy Is the Only Way To Confirm a Desmoid Tumor Diagnosis

If you notice a lump in your extremities or are experiencing any other symptoms, talk to your doctor. They will start by listening to your symptoms and performing a physical exam.

If your doctor suspects a desmoid tumor or another type of tumor, they may order one or more imaging tests, such as a computed tomography scan (CT scan) or magnetic resonance imaging (MRI). These tests allow your doctor to get a better look at the part of your body where the tumor might be located.

The imaging results will be used to decide whether a biopsy (taking a tissue sample for study) is needed. A biopsy is the only way to confirm a desmoid tumor diagnosis.

4. Some Desmoid Tumors May Not Require Treatment

Desmoid tumors in the extremities, and elsewhere in the body, may not need immediate treatment. For tumors in the hand, arm, thigh, or leg, your doctor will likely start by taking a “watch-and-wait” approach. Also known as “active surveillance,” this means observing the tumor and monitoring your symptoms over time before deciding on other forms of treatment.

This approach is favored when the tumor is not causing any immediate problems, because the tumor may stabilize or shrink on its own. If your desmoid tumor is not causing serious problems with movement, pain, or mobility, your doctor may choose to monitor the tumor over time rather than taking immediate action. However, if you are experiencing new or worsening symptoms related to walking, moving, exercising, or general mobility, be sure to speak with your health care team about it.

5. There Are Multiple Treatment Options for Desmoid Tumors

There are multiple treatment options available for people living with desmoid tumors in the hand, arm, thigh, or leg. Regardless of which treatment option you choose, it’s important to discuss your expectations for treatment with your health care team, as each treatment option comes with a different set of potential risks and side effects.

Targeted Therapies

Targeted therapies are a type of treatment that prevents tumor cells from dividing and growing.

There have been major advances in developing new treatments for desmoid tumors in the last few years. For example, in 2023, the U.S. Food and Drug Administration (FDA) approved Nirogacestat (Ogsiveo), the first FDA-approved treatment for desmoid tumors. This drug works by inhibiting the protein gamma-secretase, which helps to allow desmoid tumor cells to multiply. When gamma-secretase is blocked, the growth of desmoid tumors may be slowed.

Other targeted therapies include tyrosine kinase inhibitors (TKIs), which also work by blocking certain proteins that allow desmoid tumors to grow and divide. Some examples of TKI medications include imatinib (Gleevec) and sorafenib (Nexavar). These medications are not FDA-approved for desmoid tumors but are used off-label.

Radiation Therapy

Radiation therapy is used to treat soft tissue tumors by using intense bursts of light to kill tumor cells. It is a possible treatment option for desmoid tumors and is sometimes used alongside surgery, although this approach has become less favored in recent years.

Chemotherapy

Although desmoid tumors are different from cancer, they are treated with many of the same therapies. These include chemotherapy, which works by using drugs to kill tumor cells and prevent them from growing and dividing.

Surgery

Surgery is no longer considered a first-line treatment for many desmoid tumors because of the likelihood that the tumor will return after the procedure. However, if your tumor is causing a lot of problems or if other treatments don’t work, surgery may be a suitable option. Be sure to discuss your symptoms with your health care team to determine the best possible treatment for your desmoid tumor.

Cryoablation

Cryoablation is a nonsurgical option for treating desmoid tumors in the hands, arms, thighs, or legs. It works by applying an extremely cold substance, such as liquid nitrogen, to the abnormal tissue cells. This can be an effective treatment for shrinking the tumor size in some individuals.

6. Desmoid Tumors Sometimes Return After Treatment

It’s common for desmoid tumors to return after treatment. People living with desmoid tumors in the hand, arm, thigh, or leg should check in with their doctor regularly (typically every three to six months) to monitor any possible tumor regrowth after treatment. If you’re experiencing new or worsening symptoms after receiving treatment, let your health care team know about any changes.

Connect 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 in your hand, arm, thigh, or leg? Share your experiences in the comments below, or start a conversation by posting on your Activities page.