Tolerance and Mode of Administration of Cyto-selective Cryotherapy Treatments in Face Brown Spots: Proof of Concept

Solar lentigos or lentigines are harmless patch of darkened skin, of different sizes and colors, due to the exposure to UV radiation. They are very common, especially in people over the age of 40 years old. Solar lentigines appears as clusters of similar lesions on sun-exposed sites, such as the face or the back of the hands. Conventional cryotherapy is increasingly used to improve the skin appearance and especially to treat lentigo spots. However, the application of conventional cryotherapy is followed by temporary side effects including pain at application, hypo- and hyperpigmentation, crust, scars, burns, erythema... for a few days after administration and that can persist during several months. In this context, the sponsor has developed a treatment using cyto-selective cryotherapy, that treats only the melanocytes responsable of brown spots while preserving other cells of the epidermis. Several sequences of pulverization of cryogenic gas have been designed. It seems interesting for the sponsor to study some ways of applications of the selected sequences. i.e. 5 conditions evaluated) that could be used for the treatment of lentigos with the same clinical benefit and with better safety results for patients . (CS4\_2) proof of concept, interventional, monocentric, randomized and double blinded study, aims to evaluate the tolerance and the mode of administration of cyto-selective difluoroethane-based cryotherapy in the treatment of brown spots. The main objective of the study is to evaluate the tolerance and to adjust the mode of administration of 3 different cryotherapy treatments (3 prototypes) applied on the brown spots of the face. Each treatment corresponds to a specific sequence of a cryogenic spray.