dermatologic disorders
Overview of Pigmentation Disorders
Introduction
Melanin is the brownish pigment responsible for the color of skin, hair, and the iris of the eyes. It is produced by melanocytes. Most people have similar numbers of melanocytes, and the wide range of color shades of human skin is due to the amount of melanin that is produced rather than the number of melanocytes. There are different subtypes of melanin, the main ones in the skin being Eumelanin (brown and black types) Pheomelanin, which has a reddish hue Ultraviolet radiation, as in sunlight, stimulates melanin production, as do a number of pathologic processes. Other factors can interfere with melanin production. Pigmentation disorders involve hypopigmentation, depigmentation, or hyperpigmentation. Areas may be focal or diffuse. In hypopigmentation, pigment is decreased, whereas in depigmentation, pigment is completely lost, leaving white skin. Focal hypopigmentationis most commonly a consequence of Injury Inflammatory dermatoses (eg, Atopic Dermatitis (Eczema) , Burns None Chemical exposure (especially to hydroquinones and phenols) Focal hypopigmentation or depigmentation is also a feature of Vitiligo (which may involve large areas of skin), Diffuse hypopigmentationis most often caused by Albinism None Vitiligo None Hyperpigmentation None 