Remarkably, a large proportion of CXCL13+ FBs showed higher expression of CXCL13 than Tfh cells, likely reflecting the importance of the CXCL13+ FB subtype to the migration of B cells, and their spatial localization at the periphery of the actively inflamed areas of chronic HS lesions, potentially as TLSs. This evidence concerns the gene CXCL13 and histiocytic sarcoma.