TRIM21 and synovial sarcoma: In this patient, the presence of dry mouth and eyes, dental caries, anti-nuclear antibody (+), anti-SSA antibody (+), anti-Ro-52 antibody (+), along with a Schirmer Test ≤ 5 mm/5 min and a reduced natural saliva flow rate ≤ 0.1 mL/min, aligns with the 2016 the American College of Rheumatology and the European League Against Rheumatism Classification Criteria for Primary SS (15), confirming the diagnosis of SS.