HS is a T helper 1 (Th1)-, T helper 17 (Th17)-mediated disorder, characterized by the up-regulation of various cytokines such as tumour necrosis factor-α (TNF-α) and Th17/interleukin-23 (IL-23) [38,39,40,41]. The gene discussed is TNF; the disease is histiocytic sarcoma.