Artit Jinawath1, M.D., Ph.D., Witoo Klabtawee1, M.D., Kaettipong Kamprerasart1, M.Sc., Lalida Arsa1, M.Sc., Vorachai Sirikulchayanonta2, M.D. 1Department of Pathology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand. 2Faculty of Science, Rangsit University, Pathumthani 12000, Thailand Correspondence : Artit Jinawath Artit Jinawath M.D., Ph.D. Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, 10400, Thailand. Phone : 662-201-1667; E-mail : email@example.com Received : 10 January 2016; Accepted : 2 February 2016
Objective: Synovial sarcoma (SS) is a relatively common sarcoma of soft tissue arising in extremities of young adult, which is often diagnosed by histology and immunohistochemistry (IHC). Synovial sarcoma can be found in various locations and may cause diagnostic dilemma in tumors arising in unusual locations. In this study, we evaluated the application of molecular test namely SS18/SSX fusion transcripts as an additional diagnostic tool for synovial sarcoma. Method: We performed the reverse transcription polymerase chain reaction (RT-PCR) to detect the presence of SS18/SSX fusion transcripts in 22 tumors from various anatomical sites previously diagnosed as SS or having SS in the differential diagnoses from the years 2010 to 2014. Result: Of 22 cases analyzed, 14 cases (63.6%) were positive either for SS18/SSX1 or SS18/SXX2 fusion transcripts by RT-PCR. The remaining 8 cases (36.4%) were negative for both SS18/SSX1 and SS18/SSX2 fusion transcripts. Among 14 cases with positive molecular testing results, 12 cases were previously diagnosed as SS (85.7%), whereas the other 2 cases were originally diagnosed as other types of sarcoma (14.3%). On the other hand, from 17 cases which were initially diagnosed as SS by histology and IHC, 12 cases (70.5%) were positive for molecular test using SS18/SSX fusion transcripts, whereas 5 cases were negative. Conclusion: We found that the detection of SS18/SSX fusion transcripts by RT-PCR is a valuable method to confi rm the diagnosis of SS, especially in those diffi cult cases arising in uncommon sites or presenting with unusual histology and unconventional immunohistochemical profi les.