Dear editor,

Nail involvement occurs in approximately 10% of patients with lichen planus (LP)¹, and isolated nail affection is considered uncommon, although probably overlooked². Nevertheless, nail LP (NLP) may be severe and can rapidly worsen, potentially resulting in irreversible scarring³. In addition, treatment is particularly challenging, with high rates of failures and relapses. As a result, NLP may have a significant functional and psychosocial impact²-⁴.

We report the case of a 70-year-old female with severe refractory isolated NLP, which had started two decades earlier. All fingernails and toenails were affected (20-nail dystrophy), showing longitudinal ridging and splitting and trachyonychia (Fig. 1A). The diagnosis was confirmed by a nail matrix biopsy. The patient had been previously treated with potent topical, intralesional, and systemic corticosteroids without any significant improvement. She was later treated with methotrexate, with poor response. Baricitinib 2 mg/daily per os was thus initiated, and improvement was noted as early as the 1st month, with considerable recovery of nail changes after 3 months, showing almost complete resolution (Fig. 1B). In addition, the patient also reported significant improvement in finger motricity (due to the reduction of digital pulp pain while grabbing objects). The treatment was well tolerated, without side effects. Given the favorable response, the dosage was not increased, and the patient was kept under close clinical and laboratory follow-up.

Figure 1 A: longitudinal ridging and splitting, and trachyonychia of all the digits. B: significant improvement of the nail changes after 3 months of 2 mg/daily baricitinib, with complete resolution in some digits. 

Janus kinase (JAK) inhibitors have been revolutionizing the therapeutic armamentarium in dermatology, emerging as promising tools for inflammatory dermatoses⁵,⁶. In LP, the activation of the interferon-gamma pathway and cluster of differentiation 8 T-cell recruitment is mediated through JAK receptors, explaining the rationale for JAK inhibition in LP⁷.

Tofacitinib has been studied in patients with scalp LP⁸ and in a patient with NLP⁹, with good outcomes. A recent expert consensus has indeed highlighted tofacitinib as a promising therapy for NLP⁴. Baricitinib also proved efficacious in a patient with NLP in a recent report¹⁰.

In sum, NLP is a potentially severe and destructive disease with an unpredictable course and poor long-term prognosis. There is an unmet need for effective therapies for NLP, as no guidelines nor approved drugs are yet available. We present a severe, refractory NLP successfully treated with low-dose baricitinib without side effects in a 70-year-old female, highlighting the promising role of JAK inhibition in this scarring disorder. Additional studies and long-term follow-up are needed to strengthen its role in NLP management.