Ewing sarcoma bone tumors have an onion-skin appearance on imaging scans. This happens because the tumors stimulate the growth of a membrane that surrounds the bones.

Ewing sarcoma is a bone cancer that primarily occurs in children and teens. It’s the second most common type of bone cancer in children, following osteosarcoma.

About 1 in 3 bone cancers diagnosed in the United States are Ewing sarcomas, and 1.5 out of every 1 million children under the age of 15 develop this type of cancer.

Tumors most often develop on the pelvic and leg bones but can occur anywhere. Treatment typically includes chemotherapy, surgery, and sometimes radiation.

What is Ewing sarcoma?

Ewing sarcoma is a cancer that forms in bones and soft tissues that surround bones. It can occur in any bone, but it most commonly develops in the pelvis, legs, and upper arm bones.

Ewing sarcoma causes symptoms like pain and swelling near the tumor site, fever, fatigue, and unintentional weight loss. Children and adolescents under 30 are more at risk of this type of cancer than people of any other age group.

Read more about Ewing sarcoma here.

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On imaging tests like X-rays, Ewing sarcoma tumors can have an onion skin appearance. This happens because the tumor stimulates the periosteal layer.

The periosteal layer is a membrane that covers your bones. Injury to this layer, like an Ewing sarcoma tumor, can cause a reaction that results in layers of abnormal bone growth. This causes the onion-like appearance on imaging tests.

The first step in an Ewing sarcoma diagnosis is a medical appointment and physical exam.

During the exam, a doctor will go over your symptoms, family history, and any previous health concerns. If they suspect Ewing sarcoma or another type of bone cancer, they’ll order tests. These will include:

  • Imaging tests: Imaging tests like X-rays, CT scans, MRIs, PET scans, and bone scans can help doctors get a close look at the tumor and at any damage to bones.
  • Biopsy: A biopsy allows doctors to remove a sample of cells from the tumor and test them for cancer. This can confirm a diagnosis of Ewing sarcoma and differentiate it from other bone cancers, like osteosarcoma. Depending on the location of the tumor, your biopsy might be a needle biopsy or a surgical biopsy.
  • Gene mutation testing: The cells removed during your biopsy can also be tested for gene mutations. There are specific mutations associated with Ewing sarcoma, and the presence of these mutations can help confirm your diagnosis. Gene mutation testing can also help your doctor plan your treatment.

The treatment for Ewing sarcoma involves a combination of therapies to kill cancer cells and remove the tumor. Typical treatments include:

  • Chemotherapy: Treatment often beings with chemotherapy to shrink the tumor.
  • Surgery: Surgery to remove the tumor generally follows a round of chemotherapy. Removing the tumor will also remove the onion-skin appearance.
  • Radiation: Sometimes, radiation to kill remaining cancer cells is used after surgery.

As with all types of cancer, Ewing sarcoma has the best outlook when diagnosed and treated early. According to the American Cancer Society, the overall 5-year relative survival rate for Ewing sarcoma was 63% between 2012 and 2018. Additional 5-year relative survival rates were:

  • Early-stage tumor: 83%
  • Regional cancer spread: 71%
  • Distant cancer spread: 39%

It’s important to remember that these survival rates are based on data collected between 2012 and 2018. There have been significant improvements in treatments for Ewing sarcoma in the past decade, and it’s likely that current survival rates reflect this.

Additionally, individual outcomes are influenced by factors like age, genetics, reaction to treatment, and overall health.

Ewing sarcoma is a type of bone cancer that primarily affects children and teens.

The tumors associated with Ewing sarcoma can create an onion-skin-like appearance on imaging scans. This happens because tumors can stimulate the growth of a membrane that surrounds the bones.

Diagnosis of Ewing sarcoma helps distinguish it from other types of bone cancer, like osteosarcoma, and includes imaging tests, biopsies, and genetic testing.

Treatment to kill cancer cells and remove tumors will also remove the onion-skin appearance caused by tumors.