Among the very few SS cases with extensive ossification and available molecular testing, including information on the SSX fusion partner subtype, only SSX1 [8,10] and/or SSX2 (one case with prominent needle-shaped mitochondrial calcifications seen ultrastructurally) [7] partners have been identified with no SSX4 fusion partner identified to date. The gene discussed is SSX4; the disease is synovial sarcoma.