A chemical peel (chemexfoliation), also sometimes referred to as chemosurgery, chemexfoliation, and dermapeeling, is the application of caustic material to the skin resulting in destruction of the epidermis and/or superficial dermis in whole or part.
The three main classifications of chemical peels are characterized by the depth of the tissue injury caused are superficial, medium, and deep. The depth of area of injury created by the peel is based on several factors including the type of chemical, the concentration of the chemical, number of applications, and individuals skin type.
Superficial chemical peels, sometimes referred to as epidermal peels, only penetrate the epidermis and therefore are used in indications affecting that layer (e.g., mild photoaging, melasma, and acne vulgaris). Common types of superficial peels are alpha hydroxy acids (AHAs), such as glycolic (30%–50%), lactic (10%–30%) or mandelic (40%); beta hydroxyl acids (BHAs), such as salicylic acid (30%); and alpha 
keto acids (AKAs), such as pyruvic acid (50%). This application is commonly used to treat fine or subtle lines, lighten skin due to hyperpigmentary disorders, and improve the skin's texture and appearance.
Medium-depth peels, sometimes referred to as dermal peels, penetrate the epidermis and the papillary dermis and therefore are used in indications affecting those layers (e.g., moderate photoaging, mild acne scars, and actinic keratoses). Common types of medium-depth peels are salicylic acid (>30%, multilayer application), glycolic acid (70%, with or without pretreatment primer such as Jessner’s solution), trichloroacetic acid (TCA) (30%–50%, monolayer application, with or without pretreatment primer such as Jessner’s solution). Jessner’s solution is a primer used to optimize medium-depth peels by disrupting cornified layer (salicylic acid, 14g; resorcinol 14g; lactic acid (85%), 14g; and ethanol to 100mL). Chemical peels are appropriate when there are numerous lesions.
Deep peels, also sometimes referred to as dermal peels, penetrate the epidermis, papillary dermis, and mid-reticular dermis and therefore are used to treat indications affecting those layers (e.g., severe photoaging, deep acne scars, and premalignant skin neoplasms). Common types of deep chemical peels are TCA (>50%, monolayer application, with or without pretreatment primer such as Jessner’s solution), Baker-Gordon phenol peel (detergent, croton oil as an epidermolytic agent, phenol, and water for dilution to 50%–55% phenol).
Actinic keratoses are keratinocyte neoplasm that occur on skin that has had long-term sun exposure. Actinic keratoses are typically confined to the epidermis but can extend into the papillary dermis or reticular dermis, where they are termed as squamous cell carcinomas. The estimated progression of actinic keratoses to squamous cell carcinomas varies from 0.1% to 20%. Typical treatment options include topical creams, gels, and solutions; cryosurgery; and photodynamic therapy. Lee et al., writing in the Journal of the American Academy of Dermatology (2019), listed the indications for medium-depth peels and noted that its “penetration into the papillary dermis supports its use in the treatment of actinic keratoses.”
Cosmetic services are those provided to improve an individual's physical appearance, from which no significant improvement in physiologic function can be expected. Emotional and/or psychological improvement alone does not constitute improvement in physiologic function.
