Janus kinase inhibitors for nail lichen planus: A systematic review

Background Nail lichen planus (NLP) is a variant of lichen planus that responds inconsistently to corticosteroids, retinoids, and immunosuppressants. Its pathogenesis involves interferon-γ signaling through JAK2/STAT1, making JAK inhibition a targeted approach. We aimed to characterize nail outcomes in NLP patients exposed to JAK inhibitors. Methods PubMed/MEDLINE, Embase, Cochrane, and Web of Science were searched from inception through May 18, 2026, for JAK or TYK2 inhibitor use in diagnosed NLP. Two reviewers screened and analyzed evidence (PROSPERO CRD420261394122). Results Twelve studies reporting 22 unique JAK-treated patients were included; NLP occurred in isolation in 11. Patients received tofacitinib (14), baricitinib (4), abrocitinib (2), upadacitinib (1), or ruxolitinib (1), orally in 17 and topically in 5. Complete or near-complete response was seen in 5 patients and marked improvement in 17, over a median 8 months. Longitudinal ridging, fragility, trachyonychia, onycholysis, and subungual hyperkeratosis improved consistently. Relapse occurred in 2 patients after discontinuation and 2 after dose reduction. No adverse events were reported. Conclusions Evidence was uncontrolled and mostly limited to single-patient reports with inconsistent outcome measurement. The results support JAK inhibition for refractory NLP, with topical therapy offering a lower-exposure option. Controlled trials using standardized severity measures are needed.