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EWSR1/WT1 FISH

Also known as: Desmoplastic small round cell tumour FISH

Test category:

Oncology - Sarcoma

Use of test

Purpose:

The EWSR1 gene at 22q12 is fused with the WT1 gene at 11p13. This fusion occurs in almost all cases of desmoplastic small round cell tumour. This FISH test identifies the rearrangement.

Utility:

This test has diagnostic and prognostic implications.

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 fusion of EWSR1 and WT1. 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 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.