What are other Names for this Test? (Equivalent Terms)
- Gene Mutation Analysis for Extraosseous Ewing’s Sarcoma
- Molecular Testing for Extraskeletal Ewing’s Sarcoma
- Test for Molecular Diagnosis of Extraosseous Ewing’s Sarcoma
What is Molecular Testing for Extraosseous Ewing’s Sarcoma? (Background Information)
- Molecular Testing for Extraosseous Ewing’s Sarcoma is a genetic test that is helpful in aiding a diagnosis of extraosseous Ewing’s sarcoma. The lab test results may also be subsequently useful in taking appropriate treatment decisions
- Extraosseous Ewing’s sarcoma (EES, or extraskeletal Ewing’s sarcoma) is an Ewing’s sarcoma that occurs in the soft tissues, anywhere in the body. EES is a life-threatening and malignant soft tissue tumor that affects young children
- 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. The tumor is generally found in the soft tissues of the kidneys, abdominal cavity, intestines, and central nervous system, among other regions
The cause of extraosseous Ewing’s sarcoma is due to genetic mutations. Currently, studies indicate defects in the following genes:
- EWSR1-FLI1 causing chromosomal translocation abnormality namely t(11;22)(q24;q12)
- EWSR1-ERG causing chromosomal translocation abnormality namely t(21;22)(q22;q12)
- EWSR1-ETV1 causing chromosomal translocation abnormality namely t(7;22)(q22;q12)
- EWSR1-EIAF causing chromosomal translocation abnormality namely t(17;22)(q21;q12)
- EWSR1-FEV causing chromosomal translocation abnormality namely t(2;22)(q36;q12)
- FUS-ERG causing chromosomal translocation abnormality namely t(16;21)(p11;q22)
- FUS-FEV causing chromosomal translocation abnormality namely t(2;16)(q36;p11)
The above genetic abnormalities can be detected using molecular studies, which may play a significant role in identifying the tumor type, and in some cases, helping the healthcare provider take appropriate treatment decisions.
The molecular testing, in general, can be performed using a variety of methods. Some of these methods include:
- In situ hybridization technique, such as fluorescence in situ hybridization (FISH)
- Immunohistochemistry (IHC)
- Next-generation sequencing (NGS)
- Polymerase chain reaction (PCR)
- Comparative genomic hybridization (CGH)
- Karyotyping including spectral karyotyping
- mRNA analysis
- Tissue microarrays (TMAs)
- Southern blot test
- Northern blot test
- Western blot test
- Eastern blot test
The methodology used for extraosseous Ewing’s sarcoma may vary from one laboratory to another.
Note: Molecular testing has limitations due to the molecular method and genetic mutational abnormalities being tested. This can affect the results on a case-by-case basis. Consultation with your healthcare provider will help in determining the right test and right molecular method, based on individual circumstances.
What are the Clinical Indications for performing the Molecular Testing for Extraosseous Ewing’s Sarcoma Test?
Molecular Testing for Extraosseous Ewing’s Sarcoma is undertaken in the following situations:
- To assist (and in some cases, confirm) the initial diagnosis of extraosseous Ewing’s sarcoma
- To distinguish other tumors/conditions that have similar histological features, when examined by a pathologist under the microscope
- To help in determining treatment options
- To confirm recurrence of the tumor: Tumor recurrence can either be at the original tumor site, or at a distant location (away from the initial site)
How is the Specimen Collected for Molecular Testing for Extraosseous Ewing’s Sarcoma?
Following is the specimen collection process for Molecular Testing for Extraosseous Ewing’s Sarcoma:
The specimen sample requirements may vary from lab to lab. Hence, it is important to contact the testing lab for exact specimen requirements, before initiating the testing process.
- Sample required:
- Fresh tumor tissue during biopsy
- Formalin-fixed paraffin-embedded solid tumor tissue (FFPE tumor tissue), often referred to as paraffin block of the tumor
- Unstained tissue slides
- Process of obtaining the sample: As outlined by the laboratory testing facility
- Preparation required: As outlined by the laboratory testing facility
- Depending on the location of testing, it may take up to 2 weeks’ turnaround time, to obtain the test results
- Occasionally, additional samples may be required to either repeat the test or to perform follow-up testing
- Many hospitals preserve the paraffin blocks for at least 7 years. In general, older paraffin blocks (over 5 years) may affect the detection of specific mutations, due to degradation of the tumor specimen over time
Cost of Molecular Testing for Extraosseous Ewing’s Sarcoma:
- The cost of the test procedure depends on a variety of factors, such as the type of your health insurance, annual deductibles, co-pay requirements, out-of-network and in-network of your healthcare providers and healthcare facilities
- In many cases, an estimate may be provided before the test is conducted. The final amount may depend upon the findings during the test procedure and post-operative care that is necessary (if any)
What is the Significance of the Molecular Testing for Extraosseous Ewing’s Sarcoma Result?
The significance of Molecular Testing for Extraosseous Ewing’s Sarcoma is explained:
- Presence of a positive test result helps aid, and in some cases, confirm the diagnosis of extraosseous Ewing’s sarcoma
- The result can help exclude other tumors with similar histological features
- It can help determine the prognosis of the patient
- In some cases, the test results may help in taking treatment decisions
The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.
Additional and Relevant Useful Information:
- Many laboratories may not have the capability to perform this test. Only highly-specialized labs with advanced facilities and testing procedures may perform this test
- Additional mutations are still being discovered in many of these tumors. This may further contribute towards tumor diagnosis and treatment. Please consult with your healthcare provider for any information updates
Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider of the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.
What are some Useful Resources for Additional Information?
The following DoveMed website link is a useful resource for additional information:
Please visit our Laboratory Procedures Center for more physician-approved health information:
References and Information Sources used for the Article:
https://ghr.nlm.nih.gov/primer/testing/genetictesting (accessed on 02/17/2017)
https://www.cdc.gov/mmwr/preview/mmwrhtml/rr5806a1.htm (accessed on 02/17/2017)
http://www.nature.com/gim/journal/v10/n5/full/gim200852a.html (accessed on 02/17/2017)
http://pediatrics.aappublications.org/content/106/6/1494 (accessed on 02/17/2017)
https://ghr.nlm.nih.gov/condition/ewing-sarcoma (accessed on 02/17/2017)
https://www.hindawi.com/journals/sarcoma/2011/856190/ (accessed on 02/17/2017)
http://theoncologist.alphamedpress.org/content/11/5/503.full (accessed on 02/17/2017)
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