Pigmentation refers to the colouring of skin. Healthy skin appears normal in colour, but when there is a problem the colour may change. Skin gets its colour from melanin, a pigment that is produced by special cells called melanocytes; these occur the basal layer of the epidermis.
When the melanocytes become unhealthy or damaged the production of melanin is disrupted. Most pigmentation problems are localised and affect patches of skin, but they can be widespread and affect the whole body.
If the skin darkens it is called hyper-pigmentation, and if it gets lighter it is called hypo-pigmentation.
Hyper-pigmentation (dark skin patches)
Hyper-pigmentation happens when there is an increase in melanin. The major cause of hyper-pigmentation is exposure to sunlight though it can be caused by a number of conditions, for instance pregnancy, Addison’s disease, and the response to certain drugs including some antibiotics, anti-arrhythmic and anti-malarial drugs. Post-inflammatory hyper-pigmentation can result following various conditions such as acne, eczema, psoriasis, and dermatitis.
A common form is of Hyper-pigmentation is melasma or chloasma. This appears as brown or tan patches which generally occur on the face and forearms. It occurs in both men and women, though in women it is often caused by pregnancy and disappears after pregnancy. It can be treated by certain creams. If you have this condition then it is important to limit your exposure to the sun and use a sunscreen.
Hypo-pigmentation (light skin patches)
Hypo-pigmentation appears as light skin patches which form in areas that are deficient in melanin. There are a number of possible causes, and one of the most common is called Vitiligo and it occurs when the cells that produce melanin are damaged, and it isn’t always possible to find a cause. It could be a symptom of an autoimmune disease, and it could also have genetic causes. Although there is no complete cure for Vitiligo, there are a number of treatments including corticosteroid creams that can help considerably. If you have Vitiligo it is important to reduce exposure to sunlight and use a sunscreen in order to prevent the condition from worsening.
Hypo-pigmentation can also occur as result of skin damage, for instance a skin infection, a burn, or other trauma. Generally these will fade over time and could recover completely though this can take several years. Although there is no treatment generally the affected area can be hidden or disguised with cosmetics.