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Alternative Name
Test Description

Probes: SS18 (SYT) (18q11.2)
Disease(s): Synovial sarcoma

Clinical Significance

SS18 break-apart FISH testing detects rearrangements of SS18 (also known as SYT or SSXT) in synovial sarcoma. SS18 rearrangements are found exclusively in this tumor and have been widely used to establish an accurate diagnosis. The major translocation in synovial sarcoma is  t(X;18)(p11.2;q11.2) which results in fusion of SS18 with one of the SSX genes on the X chromosome. This translocation or complex variants are present in >95% of all cases, often as the sole abnormality. SS18 rearrangement partners will not be identified by this FISH test. For that purpose, please see the NGS Comprehensive Sarcoma Fusion Profile.

Specimen Requirements
  • Bone marrow aspirate:  N/A
  • Peripheral blood: N/A
  • Fresh, unfixed tissue: N/A
  • Fluids: N/A
  • Paraffin block: Send paraffin block. Also send circled H&E slide for tech-only (required)
  • Cut slides: H&E slide (required) plus 4 unstained slides cut at 4-5 microns. Circle H&E slide for tech-only
Storage and Transportation

Refrigerate specimen. Do not freeze. Use cold pack for transport, making sure cold pack is not in direct contact with specimen.

CPT Code(s)*
88377x1 manual or 88374x1 automated
New York Approved
Level of Service
Turnaround Time

4 days

*The CPT codes provided with our test descriptions are based on AMA guidelines and are for informational purposes only. Correct CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed.