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Ewing sarcoma FISH

Also known as: Ewing's FISH, t(11;22) FISH, primitive neurectodermal tumour, PNET, clear cell sarcoma FISH, desmoplastic small round cell tumour FISH, extraskeletal myxoid sarcoma FISH

Test category:

Oncology - Sarcoma

Use of Test

Purpose:

Ewing sarcoma is associated with breakage of the EWSR1 locus, which is seen in around 75% of cases. The EWSR1 probe detects breakage of this locus on Chromosome 22. There are a number of possible partner genes, the most frequent being FLI1 on Chromosome 11.

Utility:

This test has diagnostic and prognostic implications. Fusion of EWSR1 with the FLI1 gene, or variant partners ERG, ETV1, FEV and ETV4, are all associated with Ewing sarcoma. EWSR1 can also be involved in a rearrangement with WT1, which is associated with desmoplastic small round cell tumours, ATF1 in clear cell sarcomas of soft tissue, and NR4A3 in extraskeletal myxoid chondrosarcoma.

Ethical Considerations:

This is an assay for non-heritable mutations. It does not raise issues of ethics or consent that are different from most other investigations ordered in the routine care of a patient.

Methodology:

Fluorescent in situ hybridisation (FISH) analysis, using probes to detect gene fusions involving EWSR1. This test is performed on thin sections of tissue, so some cells in the section may be sliced by the process, and only contain some of the regions of interest. Sections may contain bony, fatty or necrotic material, which may interfere with processing and/or analysis. Dense tissue also makes identification of individual cells difficult. The accuracy of the results is dependent on the correct identification of tumour on the sections provided, and the assumption that positive results will be identified by a large proportion of cells within the tumour having a rearrangement.

Requesting the Test

Ordering:

This test is usually requested by an oncologist.

Request form:

Download the solid tumour somatic mutation request form.

Sample required:

Formalin-fixed, paraffin embedded tissue (FFPE) - 15 sections of 4 uM thickness, dried overnight at 37°C onto charged/coated slides.

Special instructions:

Please stain the first section with H&E, and label each slide with patient and block identifiers. Label the unstained sections sequentially (slides 2-15). The request should be accompanied by the somatic mutation request form (above) and a copy of the original histopathology report.

Turnaround time:

5 business days.

Price:

Up to $410.

If more information is required, the requesting clinician can call our laboratory on (07) 3377 8573.

Rebate:

This test is not rebated by Medicare. The laboratory assumes that the patient or client has provided informed financial consent for the test.

Click here for our billing policy.