SS۱۸-SSX Rearrangement in Synovial Sarcoma Using Fluorescent in Situ Hybridization: A Report from an Iranian Population and Literature Review

Background: Synovial sarcoma is an aggressive soft tissue sarcoma. It has a wide spectrum of histopathologic patterns and uncertain immunohistochemistry, rendering it a diagnostic challenge. The objective of this study was to investigate the diagnostic utility and impact of SS۱۸-SSX rearrangement evaluation in an Iranian population previously diagnosed with synovial sarcoma without such molecular tests. Method: We conducted this cross-sectional study on ۴۴ formalin-fixed paraffin-embedded tissue blocks obtained from ۲۳ synovial sarcoma patients (males, ۶۹%; mean age, ۳۶.۴ years) and ۱۱ cases with other neoplasms as negative controls. We assessed these specimens for SSX-SS۱۸ gene rearrangement by break-apart fluorescent in situ hybridization (FISH) probes. Results: FISH study showed SS۱۸-SSX fusion gene in ۱۷ (۷۳.۹۱%) cases while six (۲۶.۰۹%) cases and negative controls did not show SS۱۸-SSX fusion. Histopathologic type of tumor was significantly related to the presence of rearrangement (P=۰.۰۰۲) (rearranged: ۱۱ biphasic and six monophasic tumors; non-rearranged: three monophasic and three poorly-differentiated tumors). Conclusion: This study supports the idea that molecular studies contribute to the confirmation of synovial sarcoma diagnosis, particularly in monophasic and poorly-differentiated subtypes, which show vague immunohistochemical results.

کلیدواژه ها:

Synovial sarcoma ، Gene fusion ، Fluorescent in situ hybridization ، SS۱۸-SSX۱ fusion protein