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Test ID SSX18 Synovial Sarcoma Panel, Technical Component Only

Ordering Guidance

This test includes only technical performance of the stain (no pathologist interpretation is performed). If diagnostic consultation by a pathologist is required, order PATHC / Pathology Consultation.

Shipping Instructions

Attach the green pathology address label and the pink Immunostain Technical Only label included in the kit to the outside of the transport container.

Specimen Required

Supplies: Immunostain Technical Only Envelope (T693)

Specimen Type: Tissue

Container/Tube: Immunostain Technical Only Envelope

Preferred: 4 unstained positively charged glass slide (25- x 75- x 1-mm) per test ordered; sections 4-microns thick.

Acceptable: Formalin-fixed, paraffin-embedded (FFPE) tissue block

Useful For

Aiding in distinguishing synovial sarcomas from similar sarcomas

Testing Algorithm

For the initial technical component only immunohistochemical (IHC) stain performed, the appropriate bill-only test ID will be reflexed and charged (IHTOI). For each additional technical component only IHC stain performed, an additional bill-only test ID will be reflexed and charged (IHTOA).

Method Name

Immunohistochemistry (IHC)

Reporting Name

Synovial sarcoma panel IHC, T Only

Specimen Type


Specimen Stability Information

Specimen Type Temperature Time Special Container
TECHONLY Ambient (preferred)

Clinical Information

SS18-SSX fusion-specific antibody and SSX-C-terminal antibody are markers used for the diagnosis of synovial sarcoma.


SS18-SSX fusion-specific antibody recognizes SS18-SSX fusion proteins which are a result of the SS18 (synovial sarcoma translocation, chromosome 18) gene fusing with SSX (synovial sarcoma, X) gene on chromosome 18. This translocation is unique to synovial sarcoma. SSX-C-terminal antibody recognizes endogenous levels of SSX (1-4) proteins and the SS18-SSX fusion protein. Using these two antibodies together will aid in distinguishing synovial sarcomas from other histologically similar sarcomas.


This test does not include pathologist interpretation only technical performance of the stain. If interpretation is required, order PATHC / Pathology Consultation for a full diagnostic evaluation or second opinion of the case.


The positive and negative controls are verified as showing appropriate immunoreactivity and documentation is retained at Mayo Clinic Rochester. If a control tissue is not included on the slide, a scanned image of the relevant quality control tissue is available upon request; call 855-516-8404.


Interpretation of this test should be performed in the context of the patient's clinical history and other diagnostic tests by a qualified pathologist.

Clinical Reference

1. Baranov E, McBride M, Bellizzi A, et al: A novel SS18-SSX fusion-specific antibody for the diagnosis of synovial sarcoma. Am J Surg Pathol. 2020 Jul;44(7):922-933

2. Kadoch C, Crabtree G: Reversible disruption of mSWI/SNF (BAF) complexes by the SS18-SSX oncogenic fusion in synovial sarcoma. Cell. 2013 Mar 28;153(1):71-85

3. McBride M, Pulice J, Beird H, et al: The SS18-SSX fusion oncoprotein hijacks BAF complex targeting and function to drive synovial sarcoma. Cancer Cell. 2018 Jun 11;33(6):1128-1141

4. Thway K, Fisher C: Synovial sarcoma: defining features and diagnostic evolution. Annals of Diag Path. 2014 Dec;18(6):369-380

Day(s) Performed

Monday through Friday

Report Available

1 to 3 days

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

88342-TC, primary

88341-TC, if additional IHC

LOINC Code Information

Result ID Test Result Name Result LOINC Value
610610 Synovial sarcoma panel IHC, T Only No LOINC Needed


If not ordering electronically, complete, print, and send a Immunohistochemical (IHC)/In Situ Hybridization (ISH) Stains Request (T763) with the specimen.

Mayo Clinic Laboratories | IHC Catalog Additional Information: