Skin 101: A Guide To Melasma
Updated: Feb 23
Melasma is an unpredictable and complex form of pigmentation. It's pathogenesis (how it develops) is still not entirely understood - but we are slowly putting together the pieces of the puzzle, and treatment for this type of pigmentation has been steadily improving over the last few decades.
Melasma is by no means a new skin condition - the first disease descriptions of melasma actually date back to 360BC, around the time of Hippocrates! It primarily affects women, with 90% of cases being female - and typically appears between the ages of 20-40 years.
I'd like to preface this article with an unfortunate reality which is this: there is no cure for melasma - yet. Melasma should be thought of like any chronic disease - with the aim being control and management; reduction, rather than removal.
So what exactly is it?
Melasma is an acquired pigmentation disorder that presents as symmetrical, solid patches of pigmentation, affecting both sides of the face (bi-lateral). The most common pattern of melasma is called the "centrofacial" pattern - affecting the forehead, inner cheeks, upper lip and centre of chin.
The pigment causing this visual discolouration, is melanin. In healthy skin, melanin is normally only found in the epidermis (the outermost layer of skin). In melasma, melanin can sometimes have made its way into the dermis (the layer underneath the epidermis), making it almost impossible to remove or treat. When we talk about melasma being "epidermal" or "dermal" - we are referring to where the pigment is situated in the skin. Sometimes melasma is mostly epidermal, which makes it easier to fade (as we have better access to epidermal pigment). But most of the time, melasma is a mixture of dermal and epidermal melanin.
How does it develop?
This question comes with a pretty complicated answer. The development of melasma is still not entirely understood - but we do know of a few key factors, including: under or over expression of specific genes, oestrogen, progesterone, UV exposure, pregnancy, HRT, and hormonal contraceptives. Let's get into the details:
The Genetic Factor (TLDR available if you scroll down)
There are several genes, growth factors and proteins that have been implicated in melasma including:
- H19 / a gene thought to modulate/down-regulate melanogenesis (melanin production process). This gene is found to be down-regulated in skins affected by melasma.
The following are found to be up-regulated in melasma:
- TYR (tyrosinase encoding gene) / this gene encodes tyrosinase, an essential enzyme in the process of melanin production.
- TRP1 & TRP2 / (tyrosinase related proteins 1 & 2) these proteins are directly involved in the melanin production process.
- MITF / (micropthalmia-associated transcription factor) directly involved in melanogenesis, increases expression of TRP1 & TRP2, and tyrosinase.
Finally, KGF (keratinocyte growth factor), HGF (hepatocyte growth factor), and SCF (stem cell growth factor) / these growth factors promote melanin production in the skin.
Fibroblasts (cells that produce collagen & elastin) in photo-damaged skin produce higher levels of these growth factors, resulting in increased melanin production. This of course, IS a controllable factor - by protecting our skin from UV damage, we can prevent this process to a degree.
TLDR; there are multiple genes, proteins and growth factors involved, that all increase melanin production. Some are out of our control, and some can be avoided with good sun protection. Moral of the story, (as usual), wear sunscreen.
The UV Factor
This is one of the biggest controllable factors in the development of melasma. We all know that UV exposure causes an increase in our melanin production - but it ALSO stimulates secretion of VEGF - Vascular Endothelial Growth Factor. This growth factor stimulates formation of new blood vessels, which increases the vascularity of the skin. It's thought that this increased vascularity stimulates and supports increased melanin production in the skin.
There is also now a growing body of evidence to suggest that visible light can stimulate melanocytes to produce melanin - which is why for clients treating pigmentation, I usually suggest a sunscreen with a blue light shield (Dermaquest sheer zinc is my favourite).
The Basement Membrane Factor
The basement membrane lies between the upper layer of the skin (epidermis) and the inner layer of the skin (dermis). The basement membrane is responsible for a lot of different things, one of which being preventing melanin/melanocytes from entering the dermis.
When the basement membrane is compromised, melanin and melanocytes can "drop" into the dermis, causing dermal melanin. Once melanin is in the dermis, its very difficult to treat due to the depth at which it sits in the skin - so ideally this kind of pigmentation is to be prevented. How do we do this? We can take care of our basement membrane by:
- protecting our skin from UV exposure, which damages the basement membrane
- using topical care that supports the health and structural integrity of our basement membrane - especially vitamin A.
The Hormone Factor