Pigmentation, Discoloration, Spot
Genetic aspect of skin pigmentation
Colors are very important in our life. Most colors in biological materials are due to complex molecules, the most complex of which is Melanin .Melanin also known as pigment.
Skin color tones have Yellow, Blue, Red, and Brown. Yellow to the pigments called Carotenoids, Blue color is due to the Hemoglobin in the veins, Red is due to a blood pigment called Oxygenated hemoglobin, and last one the major brown color to the presence of the pigment melanin, which is produced melanocytes. Skin colors are a combination of melanin, hemoglobin, carotenoids and condition of the Stratum Corneum (first layer of epidermal).
Flaky skin of any color looks whiter or lighter because it can’t absorb light. What is perceived in skin color is the reflected light off the skin.
Melanin
The melanin absorbs both ultraviolet light and visible light. The more melanin in the skin, the more light is absorbed and the darker the skin looks. In the case of black skin with more melanin, the broad absorption of light by melanin allows less light to reflect, so what is seen are mainly the reflected brown hues.
It is this broad absorption band of melanin that gives black skin protective quality against ultraviolet light. Melanin functions to prevent ultraviolet radiation of black skin by absorbing the highly energetic radiation and converting the energy to heat. This explains why dark completed individuals find it uncomfortable to lie in the sun and prefer to wear clothing to cover their skin when working outdoors.
Caucasian skin, so called white skin, actually is a red-brown hue. But because Caucasian skin does not contain as much melanin as black skin, white light is reflected from surfaces that do not absorb specific colors so the total spectrum, which is white light perceived. This reduction in melanin contents results in a reduced ability of the skin to protect itself from damaging ultraviolet radiation. This explains the increased incidence of melanoma, squamous cell carcinoma, basal cell carcinoma, wrinkling and discoloration seen in light skin colors as compared to darker skin color
Adapted from Physiology of The skin By DR Draelos , MD and DR Pugliese, MD