IL17A and lichen planus: Since 2015, the emergence of biologic therapies targeting specific immune pathways—such as JAK/STAT (baricitinib, tofacitinib), IL-17 (secukinumab, ixekizumab), IL 12/23 (Ustekinumab), IL-23 (guselkumab), and TNF-α (infliximab, etanercept, adalimumab)—has marked a shift toward precision immunomodulation in refractory lichen planus.