ABSTRACT
Cutaneous hyperpigmentations can be congenital or acquired, localized or diffuse. The main pigment involved in hyperpigmentation is melanin, but others, such as hemosiderin, carotenes, and pigment secondary to drugs and tattoos, may also be involved. Melasma is a form of localized hyperpigmentation that occurs mainly on the face. Three clinical patterns of facial melasma are recognized—centrofacial, malar, and mandibular—and the melanin pigment can be located in the epidermis, dermis, or both. When performing the clinical exam, the lesion characteristics are helpful in the diagnosis: in melasma, lesions tend to be symmetrical, with irregular or geographical borders. Riehl melanosis, a pigmented dermatitis caused by contact with cosmetics applied to the face, is characterized by brownish-gray spots that predominate on the forehead and temples. The diagnosis of diseases with hyperpigmentation requires a detailed clinical examination, accompanied by a complete medical history and, sometimes, use of auxiliary methods.
