Methodology: FISH

Clinical Significance:
This FISH assay detects most rearrangements involving the EWSR1 gene irrespective of translocation partner. Genetic approaches to identify rearrangements of the EWSR gene on chromosome 22q12, characteristic of over 90% of PNET/Ewing sarcomas, have become the method of choice for confirming this diagnosis. EWSR1 gene translocation can be identified in a number of different tumors including: 1) primitive neuroectodermal tumor (PNET/Ewing sarcoma) with t(11;22)(q24;q12) involving the EWSR1/Fli-1 as well as other EWSR1 variant translocations, 2) desmoplastic small round cell tumors (DSRCT) with t(11;22)(p13;q12) involving EWSR1/WT-1, 3) clear cell sarcoma (CCS), detecting t(12;22)(q13;q12) involving EWSR1/ATF1, and 4) extraskeletal myxoid chondrosarcomas (EMCs with t(9;22)(q22;q11-12) involving EWSR1/CHN. This assay is therefore of use when these tumors are being considered in a tumor differential.

Probe type: Dual color breakapart

Organ: Soft Tissue

Disease State: Small, Blue, Round Cell Tumors, Spindle Cell Tumors / Sarcoma Subtyping

CPT Code(s): 88374 (reference only; CPTs may vary)

Turnaround Time: Within 3-4 business days of receipt

Schedule: Monday - Friday

Specimen Requirements:
• Formalin-fixed, paraffin-embedded tissue block or cell block - OR -
• Minimum of 5 unstained slide cut at 4µm for each test requested