Assessment of SS18-SSX Fusion Specific Antibody in Carcinoma and Melanoma

Synovial sarcoma, especially when poorly differentiated, can be difficult to histologically distinguish from other soft tissue sarcomas and poorly differentiated carcinomas. Several immunohistochemical stains are helpful for supporting the diagnosis of synovial sarcoma. In the past, TLE-1 was used; however, it has shown positive staining in other sarcomas and carcinomas. More recently, the fusion specific SS18::SSX antibody has been shown to be a very sensitive and specific marker in the diagnosis of synovial sarcoma. In this study, we evaluate the SS18::SSX antibody in a wide range of carcinomas. Immunohistochemical stains for SS18::SSX (Clone E9X9V, Cell Signaling, Danvers, MA, USA) fusion specific antibody were performed on five melanomas, and 100 carcinomas. None of the carcinomas or melanomas demonstrated any intensity of staining for SS18::SSX antibody. SS18::SSX fusion specific antibody is a very specific marker for synovial sarcoma. Here, we demonstrate no cross reactivity in various carcinomas. These results further support that the SS18::SSX fusion specific antibody is highly specific for synovial sarcoma.