TLE1 as a diagnostic immunohistochemical marker for synovial sarcoma emerging from gene expression profiling studies

Area of Science:

• Oncology
• Molecular Pathology
• Immunohistochemistry

Background:

• Synovial sarcoma is a soft tissue malignancy characterized by the SYT-SSX fusion oncogene.
• Current diagnostic gold standards like cytogenetics and molecular testing for t(X;18) have limited accessibility.
• Gene expression profiling consistently identifies TLE1 as a key differentiator for synovial sarcoma.

Purpose of the Study:

• To evaluate the utility of anti-TLE antibodies for immunohistochemical confirmation of synovial sarcoma.
• To assess TLE protein expression in synovial sarcoma and various mesenchymal tumors.
• To establish TLE as a reliable diagnostic marker for synovial sarcoma.

Main Methods:

• Tissue microarrays were used to examine TLE protein expression.
• Both a monoclonal anti-TLE antibody and a polyclonal anti-TLE1 antibody were employed.
• Immunohistochemical staining was performed on 94 molecularly confirmed synovial sarcomas and 40 other mesenchymal tumors.

Main Results:

• Intense and/or diffuse nuclear TLE staining was observed in 91/94 synovial sarcomas.
• Moderate TLE staining was occasionally detected in schwannoma and solitary fibrous tumor/hemangiopericytoma.
• TLE staining was infrequent and at lower levels in 40 other mesenchymal tumors.

Conclusions:

• TLE protein expression serves as a robust immunohistochemical marker for diagnosing synovial sarcoma.
• This finding aids in differentiating synovial sarcoma from other soft tissue tumors.
• Understanding TLE expression may offer insights into synovial sarcoma biology and therapeutic strategies.