In this review, we highlight the potential implications of dysregulation of the IL-23/IL-17 axis in chronic inflammatory skin diseases, including psoriasis, hidradenitis suppurativa (HS), atopic dermatitis (AD), alopecia areata (AA), pityriasis rubra pilaris (PRP), pemphigus, and systemic sclerosis (SSc). The gene discussed is IL17A; the disease is histiocytic sarcoma.