Topical JAK inhibitors in the lichen planus spectrum: a systematic review

BACKGROUND: The lichen planus spectrum includes cutaneous, scalp, pigmentary, and nail phenotypes. Topical Janus kinase inhibitors offer targeted treatment with limited systemic exposure. OBJECTIVE: To map and critically appraise clinical, safety, and molecular evidence for topical Janus kinase inhibitors across lichen planus phenotypes. METHODS: We performed a PRISMA-guided systematic review (PROSPERO CRD420251155683) searching MEDLINE, Embase, Scopus, trial registries, and other sources to 1 November 2025. Human studies of topical JAK inhibitors for cutaneous lichen planus (LP), lichen planopilaris, frontal fibrosing alopecia (FFA), lichen planus pigmentosus (LPPig), or nail lichen planus were included. Risk of bias was assessed, certainty of evidence was graded, and findings were synthesized narratively. RESULTS: Thirteen studies (n = 118 patients) and one registry trial were included. In FFA, a phase 2 double-blind, vehicle-controlled trial of delgocitinib 2% cream in 30 patients met its molecular primary endpoint and showed greater clinical improvements than vehicle over 12 weeks. Two cohorts reported improvement with topical tofacitinib 2% and topical ruxolitinib 1.5% in scarring alopecia. In cutaneous LP (n = 12), an open-label study showed improvement in lesion severity and symptoms with topical ruxolitinib. Evidence for LPPig and nail LP was limited to case reports. Topical JAK inhibitors were well tolerated with infrequent local irritation and no serious adverse events. CONCLUSIONS: Topical Janus kinase inhibitors appear promising, well tolerated, and potentially steroid-sparing, particularly in lichen planopilaris and FFA. However, the evidence remains limited, and well-designed vehicle-controlled trials are needed before routine use can be justified.