Therapeutic Outcomes of Janus Kinase Inhibitors in Refractory Nail Lichen Planus: A Systematic Review

Nail lichen planus (NLP) is a chronic immune-mediated inflammatory disorder and one of the most challenging forms of lichen planus to treat. Conventional therapies, including intralesional corticosteroids, systemic immunosuppressants, and topical agents, are often associated with high failure rates and significant adverse effects. Janus kinase inhibitors (JAKIs) have emerged as mechanistically rational therapeutic agents because of the central role of the interferon (IFN)-JAK-signal transducer and activator of transcription (JAK-STAT) pathway in lichenoid inflammation; however, their efficacy and safety in NLP have not yet been systematically evaluated. A systematic review was conducted by searching PubMed, Scopus, and Web of Science from database inception through March 2026 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. Eligible studies included patients with clinically and/or histopathologically confirmed NLP and studies reporting original patient-level data of any design. Risk of bias was assessed using the Joanna Briggs Institute (JBI) critical appraisal tools appropriate to each study design. A cumulative time-to-response model was constructed, and a random-effects meta-analysis of standardized mean change (SMC) in nail severity scores was performed where data permitted. Thirteen studies were included with a total of 25 patients. Interventions included oral and topical tofacitinib, baricitinib, abrocitinib, upadacitinib, and topical ruxolitinib. Clinically meaningful improvement was reported across all studies, with most responses occurring within three to seven months of treatment initiation. The pooled SMC was 1.65 (95% confidence interval (CI): 0-3.59), with substantial heterogeneity (I²=87.6%). No serious adverse events were reported. Overall, JAKIs appear to be effective and well tolerated in the short term for refractory NLP, supporting their potential role as rescue therapy in selected cases. However, the current evidence remains limited and heterogeneous, underscoring the need for prospective randomized controlled trials with standardized outcome measures and longer follow-up durations.