The numerous shared features of all RF isotypes, especially for SS patients without RA-positive correlations with IgA, IgG, anti-Ro/SS-A, and anti-La/SS-B levels, lead us to the conclusion that these parameters are common indications of the polyclonal B-cell activation typical in SS [10], and they become less pronounced when RA co-occurs. This evidence concerns the gene CD79A and synovial sarcoma.