Topical retinaldehyde treatment in oral lichen planus and leukoplakia

The aim of this exploratory study was to assess the efficacy of a natural metabolite of vitamin A, retinaldehyde 0.1%, vehicled in a gel in 17 patients with oral lichen planus and in 13 patients with oral leukoplakia, twice daily for 2 months. Our investigation was clinical, histological, immunohistochemical through the expression of markers of cell terminal differentiation and biochemical by using two-dimensional gel electrophoresis of cytokeratins (CK). In addition, the activity of retinaldehyde was studied ex vivo on surviving buccal mucosa. Retinaldehyde gel 0.1% showed good clinical efficacy, resulting in 6% disappearance and 82% improvement of the lesions in lichen planus and 17% disappearance and 75% improvement in leukoplakia. This was confirmed with immunohistochemistry, which revealed down-regulation of filaggrin and CK-10 as markers of terminal differentiation in both diseases. The effects of retinaldehyde in these two diseases were further demonstrated in the ex vivo surviving mucosal model, resulting in histological disappearance of keratinization in 80% of the lichen planus fragments and 40% of the leukoplakia fragments, associated with down-regulation of filaggrin and CK-10.