A Novel Variant of SYT-SSX1 Fusion Gene in a Case of Spindle Cell Synovial Sarcoma

Synovial sarcoma (SS) is a rare soft-tissue tumor that affects children and young adults. It is characterized by chromosomal translocation t(X;18)(p11.2;q11.2), which results in the fusion of the gene SYT on chromosome 18 with SSX genes on chromosome X. Heterogeneity within SS fusion junctions is rare. We report a case of a 9-year-old boy with a high-grade spindle cell sarcoma. Reverse transcriptase-polymerase chain reaction revealed a characteristic translocation of SSs. However, this sarcoma showed a longer-than-expected PCR product after gel electrophoresis. Direct sequencing of the product disclosed a novel SYT/SSX1 fusion transcript. Detection of fusion transcripts is useful for diagnostics of SS. In each case, when considering this diagnosis on the morphologic grounds an attempt to analyze the translocation using PCR should be made, including the recognition of its uncommon variants.