Another study performed in patients with primary Sjögren's syndrome (pSS) [107] has proposed that CXCL13, a chemokine produced by CD4+ Tfh cells and FDCs, represents a serum biomarker for the presence of ectopic GCs in the minor salivary glands of pSS patients (Table 3). Here, CXCL13 is linked to peeling skin syndrome.