Melasma is a skin disease characterised by patchy or generalised dark pigmentation. Basically you have clusters of melanocytes (pigment producing cells) in your skin. Healthy melanocytes produce controlled amounts pigment and feed thirty six keratinocytes equally so all get the same amount dispersed evenly. Innate pigment is like your skin’s built in sunscreen and protects against sun damage. These melanocyte clusters have receptors which light up in response to triggers e.g. contraceptive pill, fertility treatments and sun.
Once melanocytes are switched on, they overproduce pigment and become uncontrollable. The ideal scenario occurs when these pigment producing cells distribute pigment equally to all neighbouring cells. When melanocytes produce too much pigment distributed in an irregular fashion, skin starts to appears mottled.
The aim of treatment is to switch off these troublesome melanocytes otherwise they will continue to go into overdrive and spill out pigment in an erratic and uncontrolled manner.
It is widely recognised that there are two types pigment, good and bad. Light phaeomelanin or bad pigment present in pale skins is fake melanin. Emumelanin or good pigment is real melanin.
Why do light skins get skin cancer and darker skins less so?
When Phaeomelanin interacts with the sun it oxidises, explodes replicates leading to increased risk of skin cancer. Darker patients possess eumelanin. With sun exposure, eumelanin oxidises, turns brown but does not explode. As a consequence the incidence of skin cancer lessens but pigment problems or melasma are more likely.
One option is bleaching, putting something on the skin targeting aforementioned melanocytes to lighten it.
The other option is blending in a similar manner to a paint brush. You take the pigment that is produced and force it to go equally to all cells. For example in the case of freckles we blend and force the pigment into other cells.