CA6 and synovial sarcoma: All of the patients had autoantibodies associated with SS, ANA, RF, anti-Ro, anti-salivary gland protein 1 (SP1), anti-carbonic anhydrase 6 (CA6) and/or anti-parotid secretory protein (Kyriakidis et al. 2014; Shen et al. 2012, 2014).