Actinic Hyperkeratosis Treated with Retinol Combined with a Polylysine Biovector: A Case Report

Background: Actinic keratosis (AK) is a precancerous skin lesion resulting from chronic exposure to ultraviolet (UV) radiation. Current treatments are effective but often perceived as aggressive, and recurrence rates remain high. This highlights the importance of developing safe products suitable for frequent use, which are non-aggressive both for the skin and for the environment. Case presentation: We report the case of a 64-year-old male patient, living in southern France, with a Mediterranean skin type (Fitzpatrick phototype IV) and advanced baldness, presenting with a chronic hyperkeratotic lesion of the scalp evolving for more than 24 months. Histological analysis confirmed actinic keratosis. The patient was treated with a dermocosmetic formulation containing retinol encapsulated in a poly-L-lysine biovector (22.5kDa), equivalent to 3.2 × 10⁶ IU of vitamin A per gram of polylysine . Application consisted of a pea-sized amount twice daily with gentle massage of the lesion. The estimated daily dose was approximately 1280 IU of vitamin A. Result and Discussion: After 21 days, the lesion regressed completely, with partial regrowth of hair at the treated site. The treatment was well tolerated, without adverse effects. This case highlights the potential of encapsulated retinol as an adjunctive strategy in the management of AK. Retinoids are known to regulate keratinocyte proliferation and differentiation, but systemic forms are limited by toxicity and teratogenicity, while topical forms often induce local irritation. Conclusion: Encapsulated retinol in polylysine may represent a promising dermocosmetic approach for actinic keratosis. While these preliminary results are encouraging, larger clinical studies are needed to confirm efficacy and safety.