Skin pigmentation

Abstract

The colour of skin is determined primarily by the amount and distribution of melanin in it. In the absence of disease the number of melanocytes does not vary significantly between individuals, irrespective of ethnicity. Increased pigmentation (hyperpigmentation) results from an increase in melanin production and/or the number of melanocytes. It can also be secondary to exogenous substances or extravasation of chemicals deposited in the skin. Its causes can be subdivided according to whether the changes are localized to one or a small number of discrete body sites or are generalized – affecting a large proportion of the skin. Conditions leading to loss of pigment in the skin generally result from decreased melanin synthesis or absence of melanocytes. The term ‘hypopigmentation’ describes any reduction in pigment in comparison with the normal state of pigmentation for that individual; depigmentation refers to a total lack of skin pigmentation from loss of pre-existing melanocytes, for example with vitiligo. Pigmentary disorders are often associated with significant psychological and social impacts for the patient. Some disorders can be challenging and recalcitrant to treatment. Therefore, it is imperative that health professionals address underlying psychosocial impacts, which is best achieved in the context of a multidisciplinary team approach.