Tolerance of Cyto-selective Difluoroethane-based Cryotherapy

Cryotherapy is more and more used to improve skin appearance. Devices using difluoroethane, manufactured by CRYONOVE PHARMA, are already available on the local and international markets, e.g. CRYOBEAUTY MAINS and CRYOBEAUTY CORPS. However, the cryogenic gas (conventional cryotherapy - liquid nitrogen) creates a dermabrasion of the skin surface and person receiving this kind of treatment presents an impaired skin during a few days following the treatment as temporary damage of stratum corneum, erythema, scars, burns. Following the side effects occurring after conventional cryotherapy application, it seems interesting for the sponsor to select other sequences of a cryogenic spray (4 prototypes of devices) which could be used for lentigo treatment with a same benefit for the consumers without any safety outcomes. This study will assess the use of different prototypes with a sequence of application of cryogenic gas which reaches a higher temperature than those which used with the reference device, in order to increase the acceptability of the device. (CS4\_3) proof of concept, interventional, monocentric, aims to evaluate the tolerance of cryotherapy treatments applied on healthy skin on the back of the hands. The main objective of the study is to evaluate on phototype V and VI, the tolerance of 4 different conditions of cryotherapy treatments (4 prototypes) applied on healthy skin on the back of the hands.