The exact cause of Ewing sarcoma isn't known. The cancer is caused by changes in the DNA of the cells. These changes aren't passed on from parents to children. They happen by chance.

Symptoms can vary in each child. They can include:

• Pain around the site of the tumor that may come and go, but gets worse over time and with activity
• Swelling around the site of the tumor
• A lump (mass)
• A bone breaks for no known reason
• Fever
• Weight loss
• Feeling tired

The symptoms of Ewing sarcoma can be like other, more common health conditions. Make sure your child sees a healthcare provider for a diagnosis.

Your child's healthcare provider will ask about your child's health history and symptoms. They will examine your child. Your child may be referred to a specialist. This may be a bone specialist (orthopedic surgeon) or a bone cancer specialist (orthopedic oncologist). Your child may have tests such as:

• X-ray . An X-ray uses a small amount of radiation to take pictures of bones and other body tissues.
• Blood tests. The blood may be tested to look for signs of Ewing sarcoma. They also help get an idea of your child's overall health.
• CT scan. This test uses a series of X-rays and a computer to make detailed images of the inside of the body.
• MRI. Large magnets, radio waves, and a computer are used to make detailed images of the inside of the body.
• Bone scan. A small amount of radioactive dye is put into your child's blood through a vein. The whole body is then scanned. The dye shows up in areas of bone where there may be cancer.
• Positron emission tomography (PET) scan. For this test, a radioactive sugar is put into the blood. Cancer cells use more of the sugar than normal cells, so it collects in cancer cells. A special camera is used to see where the radioactive sugar is in the body. A PET scan can sometimes find cancer cells in other parts of the body, even when they can’t be seen by other tests. This test is often combined with a CT scan. This is called a PET/CT scan.
• Bone marrow aspiration or biopsy. Bone marrow is the spongy center of some bones. It’s where blood cells are made. A small amount of bone marrow may be taken out with a needle. This is called aspiration. Or a solid core bone marrow tissue may be taken. This is called a core biopsy. Bone marrow is most often taken from the hip bone. This test may be done to see if cancer cells have spread into the bone marrow.
• Tumor biopsy. A biopsy is done by taking out a small piece (sample) of the tumor. It might be done with a needle or by a surgical cut (incision). The sample is sent to a lab and tested for cancer cells. A biopsy is needed to diagnose sarcomas. 

After a diagnosis of Ewing sarcoma, your child may need other tests. These help the healthcare providers learn more about the cancer. They can show how much and how far the cancer has spread (metastasized) in your child's body. A stage grouping is then assigned.

Treatment depends on the stage and other factors. Ewing sarcoma can be treated with any of these. Many times, more than 1 treatment is used:

• Surgery. Surgery may be done to remove the tumor. Surgery methods used are often able to save an arm or leg so that it doesn't need to be amputated. This is called limb-salvage or limb-sparing surgery.
• Chemotherapy (chemo). This treatment uses strong drugs that kill cancer cells. Chemo is often given before surgery. It may also be given after surgery. Chemo is given in cycles with periods of rest.
• Radiation therapy. These are high-energy X-rays or other types of radiation. Radiation is used to kill cancer cells or stop them from growing. It may be used when it's hard to take out all of the tumor with surgery.
• High-dose chemotherapy with a stem cell transplant. Young blood cells (stem cells) are taken from the child or from someone else. Then high doses of chemotherapy are given. This damages the bone marrow. After the chemo, the stem cells are replaced. This treatment may be used when there's a high risk of cancer coming back.
• Clinical trials. Ask your child's healthcare provider if there are any treatments being tested that may work well for your child. Most children with cancer are treated as part of a clinical trial. This allows them to get the best treatment available, along with treatments that are thought to be even better.

With any cancer, how well a child is expected to recover (prognosis) varies. Keep in mind:

• Getting medical treatment right away is important for the best prognosis. Cancer that has spread is harder to treat.
• Ongoing follow-up care during and after treatment is needed.
• New treatments are being tested to improve outcomes and to lessen side effects.

A child may have complications from Ewing sarcoma or from treatment, such as:

• Infection
• Bleeding
• Loose or broken grafts or rods from limb-salvage surgery
• Hair loss, mouth sores, nausea, vomiting, diarrhea, increased infections, easy bruising and bleeding, and feeling tired from chemotherapy
• Burns, hair loss, nausea, diarrhea, poor bone growth, organ damage, and new cancers from radiation
• Emotional and physical challenges from dealing with the tumor, surgery, or other needed treatments
• Heart and lung problems
• Problems with growth and development
• Learning problems
• Changes in sexual development
• Problems having children in the future (infertility)
• The cancer comes back
• Growth of other cancers later in life

A child with a Ewing sarcoma needs ongoing care. Your child will be seen by oncologists and other healthcare providers to treat any late effects of treatment and watch for signs or symptoms of the tumor returning. Your child will be checked with imaging tests and other tests. And your child may see other healthcare providers for problems from the tumor or from treatment. For instance, your child may need therapy to help with movement and muscle strength. This may be done by physical and occupational therapists.

You can help your child manage treatment in many ways. For instance:

• Your child may have trouble eating. A dietitian may be able to help.
• Your child may be very tired. They will need to balance rest and activity. Encourage your child to get some exercise. This is good for overall health. And it may help to lessen tiredness.
• Get emotional support for your child. A counselor, psychologist, or child support group can help.
• Make sure your child attends all follow-up appointments.