Successful Treatment of Nail Lichen Planus with a Lacquer Containing Urea, Keratinase, and a Retinoid Molecule: Report of 10 Cases

Lichen planus is chronic inflammatory mucocutaneous disease. Involvement of nails (nail lichen planus: NLP) could be the only manifestation or it could be associated with the other typical skin and mucous localizations. Typical NLP alterations are linear nail bed dyschromia, longitudinal ridging, splitting, onycholysis, and subungual hyperkeratosis. Pterygium could be observed in advanced stages. Treatment of NLP is challenging. Limited clinical data have suggested that both oral and topical retinoids could be beneficial. Recently, a nail lacquer containing urea (20%), keratinase from Bacillus licheniformis, and hydroxipinacolone retinoate (U-KR lacquer) has been available. This product has shown good efficacy in the treatment of onychodystrophy characterized by onychogryphosis. We have evaluated, in a case series pilot study, the efficacy of this lacquer in subjects with moderate NLP. The product was applied once daily on the affected nails. Ten subjects (6 men and 4 women, mean age 38 years) after their written informed consent, with clinical NLP (2 subjects with histological confirmation) affecting foot or hand nails (mean number of nails involved: 4; range from 1 to 10), were treated for 12 consecutive weeks with U-KR, one application per day. The main endpoint was the evolution of a NLP severity score (NLPSS) evaluating 7 nail signs: grade of onycholysis, longitudinal ridging, splitting, grade of subungual hyperkeratosis, nail bed thickening, dyschromia, and nail pitting. For each item, a 4-grade score (from 0: no sign to 3: severe) was used (range of NLPSS from 0 to 21). At baseline, the NLPSS was 20.8 ± 3. After 12 weeks, the NLPSS showed a significant reduction to 4 ± 8.8, representing an 81% reduction in comparison with baseline value (p = 0.0001), with an absolute difference between means of −16.86 ± 2,586 (95% CI of the difference: from −22.49 to −11.22) The product was very well tolerated. This 10-case pilot study suggests that a nail lacquer with 3 components (urea, keratinase, and a retinoid molecule) could be useful in subjects with NLP. Future controlled trials are warranted to better define the therapeutic potential of this product in NLP treatment.