Publication: The determination of agreement between transducer-like enhancer split-1 (TLE-1) and fluorescence in situ hybridization (fish) in synovial sarcoma cases
Date
2018
Authors
Salehan, Noraziah
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Abstract
The emergence of transducer-like enhancer of split 1 (TLE-1) as a new immunohistochemical (IHC) marker for synovial sarcoma (SS) have recently offered an alternative diagnostic strategy to pathologists in differentiating SS from other histologic mimics. Our major aim is to determine the agreement between TLE-1 IHC expression with the translocation X;18 in fluorescence in situ hybridization (FISH) for diagnosing SS. However, due to poor t(X;18) FISH signal, this paper describes troubleshooting plans for FISH analysis that were carried out in determining positive signals for t(X;18). We conducted a cross sectional study using 27 archived formalin-fixed paraffin embedded tissue blocks of synovial sarcoma, which was diagnosed in Hospital Universiti Sains Malaysia from year 1999 to July 2017. Histology assesment was performed to identify SS morphology subtypes. All samples were stained for TLE-1 by immunohistochemistry (IHC) and correlate morphology subtypes. In addition, (FISH) study were performed on formalin-fixed paraffin embedded tissue sections using break-apart SYT probe ,which hybridized to target the breakpoint gene. Troubleshooting for FISH were carried out in obtaining positive t(X;18) signal in SS cells From IHC analysis, 74.1% (20 cases) of synovial sarcoma showed positive nuclear immunoreactivity to TLE-1. Strong nuclear immunoreactivity (3+) was 48.% and moderate nuclear immunoreactivity (2+) was 25.9%. Seven cases (25.9%) were negative to TLE-1 (score 0 or 1+). The cases with no nuclear staining (0) was 18.5% and weak nuclear immunoreactivity (1+) was 7.4%. TLE-1 expression was not statistically significant with tumour morphology subtypes. Due to poor t(X;18) FISH signal, several troubleshooting plans were carried out i.e. pretreatment step, enzyme digestion and hybridization step, which the steps are known to be very sensitive to temperature, time and pH. TLE-1 is a useful marker in diagnosing SS and to distinguish from its histological mimickers. The final diagnosis of SS is only by pathologist eyes, as we still rely on morphology and IHC interpretation. The presence of agreement between TLE-1 IHC and its gold standard test (FISH) is a ticket for not to proceed with the later, which is more laborious and expensive. However, failure of signal detection due to technical and wrong methodology, we unable to proof the agreement.
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Keywords
Sarcoma , Synovial