CALR and synovial sarcoma: Previous studies hold that the infiltration of CD4+ T lymphocytes and B lymphocytes into EGs, where they form ectopic germinal centers (EGC). EGC are functional structures formed by the abnormal aggregation of immune cells in the EGs of SS patients, and serve as a key hub for the production of autoantibodies such as anti-SSA/Ro and anti-SSB/La and the maintenance of chronic inflammation. The excessive activation of B lymphocytes has been identified as a hallmark feature of SS [10-12].