Transducer-like Enhancer of Split 1 as a Novel Immunohistochemical Marker for Diagnosis of Synovial Sarcoma

Background: Synovial sarcoma is a mesenchymal neoplasm that accounts for around 10% of all softtissue sarcomas. The diagnosis of synovial sarcoma can be a challenging task, particularly with small biopsyspecimens. Aim: We investigated transducer-like enhancer of split 1 (TLE1), monoclonal antibody, expressionby immunohistochemical analysis in a group of 74 synovial sarcoma cases, 20 cases of MPNST, 12 cases ofneurofibroma, 15 cases of schwannoma, 5 cases of MFH, 10 cases of lieomyosarcoma and 10 cases of solitaryfibrous tumor. Materials and
Methods: Whole tissue sections were examined: (39 biphasic and 35 monophasic).Nuclear immunoreactivity was scored as negative (<5% of cells positive), 1+(mild /5-25%), 2+ (moderate/25-50%),and 3+ (strong >50%).
Results: Overall, 71 (96%) of 74 synovial sarcomas were positive for TLE1, including 37biphasic (95%) and 34 monophasic (97%) tumors. Other spindle cell tumors showed very low or absent stainingof TLE1.
Conclusions: We conclude that TLE1 is a sensitive marker and can be a useful diagnostic marker forsynovial sarcoma, particularly the monophasic forms.