Postinflammatory hyperpigmentation: Review of pathogenesis, prevention, and treatment

Postinflammatory hyperpigmentation (PIH) is a common pigmentary disorder that is distressing to patients, particularly those with skin of color, and can be very difficult to treat. Part of this difficulty arises from the dermal melanosis in addition to the epidermal hyperpigmentation. This article reviews the mechanisms that induce the hyperpigmentation including inflammatory mediators such as metabolites of arachidonic acid and reactive oxygen species (ROS) and how these may influence prevention and treatment strategies. Treating the inflammatory cause and sun protecting are crucial to effective therapy. Although common, few studies have been done focusing on prevention and treatment of this disease. Topical therapies are the mainstay of treatment for PIH, but have shown poor efficacy for the dermal hyperpigmentation component. Hydroquinone in combination with topical steroids, retinoids, glycolic acid, and lactic acid have been augmented with numerous emerging natural therapies such as kojic acid, arbutin, ascorbic acid, soy, and niacinamide. Although efficacious for hyperpigmentation, most of the natural therapies have not been studied specifically for PIH. Salicylic acid and glycolic acid chemical peels, as well as the quality-switched (QS) neodymium-doped yttrium aluminum garnet (Nd: YAG), QS Ruby, 1550 nm erbium fiber fractional thermolysis, and 1927 nm fractional thulium fiber lasers have shown good efficacy for the treatment of facial hyperpigmentation.