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Extraosseous Ewing’s Sarcoma (EES)

Last updated Sept. 11, 2018

Approved by: Krish Tangella MD, MBA, FCAP


Microscopic pathology image showing Extraosseous Ewings sarcoma with positive staining for CD99 IHC.

What are the other Names for this Condition? (Also known as/Synonyms)

  • EES (Extraosseous Ewing’s Sarcoma)
  • Extraosseous Ewing’s Tumor

What is Extraosseous Ewing’s Sarcoma? (Definition/Background Information)

Ewing’s Family of Tumors includes the following tumors:

  • Ewing’s Sarcoma of Bone
  • Extraosseous Ewing’s Tumor
  • Primitive Neuroectodermal Tumor (PNET), including Medulloblastoma - Adult type and Medulloblastoma - Childhood type
  • Askin’s Tumor: This tumor is also sometimes called, Primitive Neuroectodermal Tumor of Chest Wall, and Ewing’s Sarcoma of Chest Wall
  • Primary Cutaneous Ewing’s Sarcoma (PCES)

All the above-mentioned tumors arise from a primitive stem cell.

  • Extraosseous Ewing’s Sarcoma (EES) is Ewing’s Sarcoma that occurs in the soft tissues, anywhere in the body
  • When Ewing’s Sarcoma originates in the bone, it is called Ewing’s Sarcoma of Bone; when it originates in the soft tissues, it is called Extraosseous Ewing’s Sarcoma
  • EES is a life-threatening and malignant type of soft tissue tumor that affects young children
  • It is generally found in the soft tissues of the kidneys, abdominal cavity (retroperitoneum), intestines, and central nervous system, among other regions
  • It is believed that the tumor is caused by genetic defects on chromosome 11, chromosome 22, chromosome 8, and chromosome 12
  • However, with a global incidence rate of less than 1 in 500,000, Ewing’s Family of Tumors are rare types of tumors
  • The treatment modalities used to treat this tumor are surgery, chemotherapy, and radiation therapy. The prognosis depends on the stage of the tumor; metastatic tumors have a poor prognosis

Who gets Extraosseous Ewing’s Sarcoma? (Age and Sex Distribution)

  • Children and young adults 5-20 years old are primarily affected by Extraosseous Ewing’s Sarcoma (in about 80% of the cases)
  • Adults over the age of 30 years, are highly unlikely to get this condition
  • Boys are affected more commonly than girls, in a 7:5 ratio
  • Caucasians are more prone to Extraosseous Ewing’s Sarcoma, than Asians, Africans, and Afro-Americans, by a factor of 10. Hence, EES is rarely seen in African Americans and Asians

What are the Risk Factors for Extraosseous Ewing’s Sarcoma? (Predisposing Factors)

  • Genetic mutations could be a possible causal factor for Extraosseous Ewing’s Sarcoma
  • Prior radiation therapy for a completely different tumor may cause the development of EES, at the site of radiation therapy

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Extraosseous Ewing’s Sarcoma? (Etiology)

  • Extraosseous Ewing’s Sarcoma display recurrent chromosomal translocation (between chromosomes 11 and 22) with minor chromosomal anomalies (on chromosomes 8 and 12)
  • Specific translocations between chromosomes 11 and 22 is present, in over 85% of the patients
  • Such genetic mutations are known to have potentially cancerous traits. However, a specific reasons for these mutations to occur, is not established yet

What are the Signs and Symptoms of Extraosseous Ewing’s Sarcoma?

The presentations are based on the location of the soft tissue involved by the tumor. Signs and symptoms of Extraosseous Ewing’s Sarcoma may include:

  • Fever, which may be observed frequently, may indicate an infection
  • Anemia (low red cell count in blood); leukocytosis (above normal levels of white blood cells)
  • Increased blood erythrocyte sedimentation rate
  • EES tumors are generally found in the soft tissues of the kidneys, abdominal cavity (retroperitoneum), intestines, gastrointestinal tract, central nervous system, chest wall, and fingers

How is Extraosseous Ewing’s Sarcoma Diagnosed?

Diagnostic tools for Extraosseous Ewing’s Sarcoma include:

  • Physical exam with complete medical history evaluation
  • MRI scans, CT scans, to examine magnitude of the tumor mass and its spread
  • Biopsy of tumor - the specimen is examined under a microscope by a pathologist, to arrive at a definitive diagnosis
  • Genetic tests and analysis, to test for specific mutations associated with EES

Differential diagnosis, to eliminate the following tumor types may be considered, before arriving at a definitive diagnosis:

  • Dedifferentiated synovial sarcoma
  • Desmoplastic small round cell tumors
  • Lymphoma
  • Medulloblastoma
  • Mesenchymal chondrosarcoma
  • Rhabdomyosarcoma
  • Small cell osteosarcoma

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Extraosseous Ewing’s Sarcoma?

Complications due to Extraosseous Ewing’s Sarcoma are:

  • Metastasis of the tumor to other vital body organs, such as the lungs and bone marrow
  • Damage of the bones, vital nerves, and blood vessels, during surgery
  • Side effects from chemotherapy (such as toxicity), radiation therapy
  • Recurrence of the tumor after treatment

How is Extraosseous Ewing’s Sarcoma Treated?

Treatment measures for Extraosseous Ewing’s Sarcoma include the following:

  • The treatment protocol that is planned by a team of healthcare professionals is based on a variety of factors, such as:
    • The tumor stage
    • Location of the tumor
    • Tumor size
    • And whether the tumor has metastasized
  • Any combination of chemotherapy, radiation therapy and invasive procedures are used to treat this tumor. Generally, the treatment is administered at a medical center that has prior experience in treating such tumors

How can Extraosseous Ewing’s Sarcoma be Prevented?

  • Current medical research have not established a way of preventing Extraosseous Ewing’s Sarcoma
  • Genetic counseling and genetic testing could help those individuals having a family history of the condition, planning for a child
  • Regular medical screening at periodic intervals with blood tests, scans, and physical examinations, are mandatory for those who have already endured EES
  • Besides, due to its high metastasizing potential, often, several years of active vigilance is necessary

What is the Prognosis of Extraosseous Ewing’s Sarcoma? (Outcomes/Resolutions)

  • The prognosis is better if Extraosseous Ewing’s Sarcoma is:
    • Diagnosed at an early stage
    • Features a small-sized tumor that has not spread to other areas
    • The individuals’ response to the treatment procedure is good
  • Over 65% of children, who have localized EES (low-stage tumors) survive for a longer period
  • The tumors that occur in the soft tissues, which are easily accessible to surgery, have a better prognosis, than those tumors affecting tissues that are difficult to access for surgery
  • If the tumor has spread to other parts of the body, then less than one-third of the individuals, survive the condition
  • Improved outcomes have been obtained with radiotherapy and chemotherapy and the survival rate is above 40%

Additional and Relevant Useful Information for Extraosseous Ewing’s Sarcoma:

  • Extraosseous Ewing’s Sarcoma and its management can cause physical and emotional distress. Often, supportive care and encouragement help positively in bringing about a measure of relief, to the patients
  • Both, Ewing’s Sarcoma and Primitive Neuroectodermal Tumor, are round cell sarcomas (types of cancer), with ES lacking neuroectodermal differentiation, while PNET presents such features
  • It is estimated that 200 new cases of Ewing’s Family of Tumors are diagnosed newly in the US per year

What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Feb. 2, 2014
Last updated: Sept. 11, 2018