An intriguing observation in SS is that the specific gene fusion (SYT–SSX1 vs. SYT–SSX2) correlates strongly with the tumor phenotype (monophasic vs. biphasic histology, as defined by the presence of glandular epithelial differentiation with lumen formation), and almost all BSS has been shown to harbor the SYT–SSX1 fusion gene [13, 14]. The gene discussed is SSX1; the disease is synovial sarcoma.