Key candidate genes involved in psoriasis pathogenesis and linked to the IL‐17A pathway were markedly overexpressed in HS lesional skin compared to non‐lesional and healthy skin, including DEFB4A, LCN2, S100A7A, CXCL8, and CXCL5 (all Figure 2B). The gene discussed is IL17A; the disease is histiocytic sarcoma.