Chemical peeling for acne and melasma: current knowledge and innovations.

The skin is a dynamic organ that continuously eliminates an infinite number of keratinized cells through physiological mechanism. Chemical peeling is a widely used cosmetic procedure in medical practice. This technique consists of the application of one or more chemical ablative agents to the skin's surface in order to induce keratolysis or keratocoagulation. Exfoliation is followed by skin and epidermal regeneration from the adjacent epithelium and skin adnexa. Moreover, through an inflammatory reaction and the activation of the inflammation mediators, an increase in fibroblastic synthesis and in the production of new collagen and glycosaminoglycan fibers is induced. After the first treatment session, the appearance and the texture of the skin are significantly improved. Peeling agents may be divided into superficial (epidermis-papillary dermis), medium-depth (papillary to upper reticular dermis) and deep subtypes based on the depth of their penetration (mid-reticular dermis). Superficial peel is mainly used for dyschromia, acne, post-inflammatory hyperpigmentation, melasma and actinic keratosis. Medium depth peel mainly treats solar keratosis or lentigines, pigmentary disorders and superficial scars. Skin photo-ageing, deep scars or wrinkles and precancerous skin lesions require a deep chemical peeling. The aim of this article is to review recent advances in chemical peel of melasma and acne.