Pigmentary Abnormality

Uneven skin pigmentation can effect large areas of skin such as face and or more localised areas of hyperpigmentation that occur when an excess of melanin forms deposits in the skin, usually caused by inflammation, excessive sunlight, hormone treatments, aging process etc. The colour of the skin and its intensity depend on the rate of formation of the melanin, the speed of exfoliation and the thickness of the horny layer, which contains the most pigment.


Skin lightening cosmetics are used for their general lightening effects and for evening out skin tone. At one time chemical bleaches were used but today the more responsible approach to chemical correction of areas of hyperpigmentation is to inhibit melanin synthesis. Epidermal pigments are mixtures of the orange phaemelanin and the brown black eumelanin. The melanogenic pathway leading to these biopolymers starts with the amino acid tyrosine and is under control of the enzyme tyrosinase. Inhibition of this tyrosinase, which is located in the basal layer of the melanosomes, prevents the formation of the two melanin biopolymers. 


Inhibiting melanin production does not result in a noticeable reduction in pigmentation in the first few weeks but because the skin naturally renews itself every 28 days so pigmentated cells are gradually sloghed off and keratinocytes with less melanin are brought to the surface, giving the skin a lighter, more even toned complexion. Many treatments try and accelerate this process by exfoliation, using either abrasive scrubs or chemical peels, but this leaves the skin more sensitive to solar radiation so a high factor sunscreen is essential. 


In fact, whatever method is used to lighten skin the work of weeks can be undone by one high dose of sunlight.