Disorders of Pigmentation

Abstract

The color of the skin is due to a number of factors. Melanin is responsible for the shades of brown, eumelanin for brown and black, and pheomelanin for red pigmentation as seen in red heads; the pink color of untanned Caucasoid skin is due to oxyhemoglobin. Other substances responsible for skin color are the carotenes, found in the subcutaneous fat and stratum corneum. The blue color of blue naevus is due to an optical effect from melanin transmission through the skin. Optical effects are also responsible for other colors such as purple in lichen planus. There are a number of endogenous and exogenous substances responsible for skin color. Excess bilirubin in jaundice is an endogenous pigment and, skin tattooing and henna are some of the exogenous pigments.