ABSTRACT
Drug-induced hyperpigmentation is a predictable side effect and is related to the pharmacologic action of the drug; hence, this type of reaction is considered nonimmunologic. Drug-induced hyperpigmentation may be caused by dermal and epidermal deposition of drug metabolites, hemosiderin, melanin, or a combination of pigment types. The pathogenetical mechanisms of drug-induced pigmentation are variable according to the causative medication and can involve an accumulation of melanin. Clinical features are very variable according to the triggering molecule, with a large range of patterns and shades that are sometimes more or less reminiscent of the culprit drug. Hyperpigmentation is certainly the most frequently reported and one of the most impressive cutaneous adverse effects of this category of drugs. Histological findings are very variable as well, but the colored particles are often concentrated within dermal macrophages that are sometimes localized in a distinctive fashion with respect to dermal structures such as vessels or adnexes.
