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Rhabdomyosarcoma (RMS)

What Is Rhabdomyosarcoma (RMS)?

Rhabdomyosarcoma (RMS or "Rhabdo") is a cancerous tumor that develops in the body's soft tissues, usually the muscles. It can affect the head, neck, bladder, vagina, arms, legs, trunk, or just about any body part. Cells from rhabdomyosarcomas are often fast growing and can spread (metastasize) to other parts of the body.

Rhabdomyosarcoma (rab-doe-myo-sar-KO-muh) is the most common type of soft-tissue cancer in children. Kids can develop it at any age, but most cases are in kids between 2 and 6 years old and 15 and 19 years old. Boys tend to be affected slightly more often than girls.

Treating RMS usually includes a combination of chemotherapy, surgery, and radiation. With early detection and timely treatment, most kids make a full recovery.

Types of Tumors

The two main types of RMS in kids are:

  1. Embryonal RMS: This tumor usually develops in the head and neck area, genitals, or urinary tract. It typically affects kids younger than 6. Although it's an aggressive (fast-growing) type of tumor, most cases of embryonal RMS respond well to intensive treatment. A smaller percentage of low-risk kids can do very well with markedly reduced therapy.
  2. Alveolar RMS: This type, which is more likely to happen during the teen years, most often affects the arms or legs, chest, or abdomen. It, too, is fast-growing but is harder to treat. Kids with alveolar RMS need intensive treatment and do not fall into the low-risk category.

What Causes Rhabdomyosarcoma (RMS)?

The cause of RMS isn't clear, but doctors know that certain medical conditions can make some children more likely to develop it. These include genetic conditions like:

  • Li-Fraumeni syndrome, a rare genetic disorder that makes a person likely to develop cancer at some point in their life
  • Neurofibromatosis, a condition that causes tumors to grow on nerve tissue
  • Beckwith-Wiedemann syndrome, a congenital (present at birth) disorder that can cause too much growth in the body, including the internal organs
  • Costello syndrome and Noonan syndrome, both of which can cause deformities, developmental delays, and other problems
  • DICER1 syndrome, a genetic disorder of multiple organs that is often first discovered when a person develops embryonal RMS of the reproductive system

What Are the Signs and Symptoms of Rhabdomyosarcoma (RMS)?

Symptoms of RMS depend on the size and location of the tumor. Sometimes a lump may appear on a child's body and there may be swelling, often without pain. Other times, the tumor may be so deep within the body that it causes few if any symptoms.

Rhabdomyosarcoma in the head may cause headaches, bulging of an eye, or a droopy eyelid. In the urinary system, RMS affects urination (peeing) and bowel movements, and can lead to blood in the pee or stool (poop). If a muscle tumor is pressing on a nerve, a child might feel tingling or weakness in that area.

How Is Rhabdomyosarcoma (RMS) Diagnosed?

If a doctor thinks a child has RMS or another soft-tissue tumor, he or she will do a thorough physical exam and order these tests:

  • Imaging studies. These will likely include a CT scan, MRI, and maybe an X-ray, bone scan, PET scan, or ultrasound. Not only will these tests help find the size and location of the tumor, they also can determine if cancer has spread (metastasized).
  • Biopsy. For a biopsy, a sample of a lump, a sore, or tissue is taken from the body for close examination. This helps doctors make a diagnosis and choose the right treatment. The tumor might sometimes be removed completely, if possible. 
  • Blood tests. Tests such as a complete blood count, liver function panel, and blood chemistries can give important information about how well the liver and other organs are working and make sure the body can handle and process the chemotherapy. If the doctor thinks the tumor is related to an underlying genetic condition, some genetic tests also may be done.
  • Bone marrow aspiration and biopsy. Bone marrow is the spongy tissue inside bones that makes blood cells. This procedure involves removing a small amount of bone marrow tissue and examining it for cancer cells. 

How Is Rhabdomyosarcoma (RMS) Treated?

Treatment of RMS and other soft-tissue tumors depends on staging. Staging helps determine the extent of the cancer and whether it has spread to other parts of the body. Knowing the stage of the disease helps doctors decide how to treat it. 

Staging takes into account details like the size of the tumor (or tumors), how deeply the tumor has penetrated an organ, the area of the body where the cancer began, and whether the tumor has spread to other organs. In RMS, the location of the original tumor tells doctors a lot about how the tumor will behave.

Other information (like the type of tumor and the child's age and overall health) also helps doctors develop treatment plans. Those plans can include the following options, in combination or alone:

  • Surgery. When the tumor is in an area that doctors can reach safely, surgery is done to remove as much of the tumor as possible.
  • Radiation. This treatment uses high-energy radiation from X-rays, gamma rays, or fast-moving subatomic particles (called particle or proton beam therapy) to target and destroy cancer cells. Besides killing cancer cells, radiation therapy also can harm normal cells, causing physical side effects like fatigue (tiredness), nausea, and hair loss. Most side effects go away once treatment has ended. During treatment, the health care team carefully monitors radiation doses to protect healthy tissue as much as possible. This helps reduce long-term effects.
  • Chemotherapy. In contrast to radiation, which destroys the cancerous cells of a tumor in a specific area of the body, chemo works to treat cancer throughout the body. Often, several chemotherapy drugs are combined to attack the cancer cells in different ways. Like radiation, side effects are likely but will ease once treatment ends. Potential long-term effects after chemo are also discussed and monitored after treatment ends.

What Else Should I Know?

You're not alone. To find support for yourself or your child, talk to your doctor, a hospital social worker, or a child life specialist. Many resources are available that can help you get through this difficult time. You also can find more information and support online at:

Reviewed by: Scott M. Bradfield, MD, MBA
Date Reviewed: Nov 15, 2021

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