Melasma
The word melasma comes from the Greek “Melas” in allusion to a dark colour.
It consists of an acquired hypermelanosis, generally present on both sides of the face. The factors that affect its apparition are anovulants, pregnancy, genetics, and exposure to the sun as well as menopause.
Anovulants are composed of oestrogens and progestins that reproduce a state of artificial pregnancy. Pregnancy stimulates melanostimulant hormones.
Despite the application of protective creams, the exposure to the sun can cause peroxidation in the lipid cell membranes. This generates free radical that can stimulate an excess production of melanin. Melanin is a dark pigment produced in the melanosomes from tyrosine, the amino acid that stimulates pigmentation.
Types of melasma
There are three types of melasma, according to the depth of the melanin:
·Dermal: where the melanin is located on the skin’s surface. Its edges are usually diffuse and they normally can be found in the zygomatic bone region.
·Epidermal: the melanin is located in the most basale epidermal layers. The edges are well-defined and tend to be distributed in the central-facial region. This type of melasma responds best to the treatment.
·Combined: combines the features of the dermal epidermal melasmas.
A Wood’s Lamp allows for diagnosis and classification of the melasma. This tool emits short wave ultraviolet light between 330 and 365 Nm. The melasma is more visible under the Wood’s Lamp light. It also allows for differential diagnosis to discern between the epidermal (becomes darker under Wood’s Lamp light) and the dermal melasma (which clarifies under Wood’s Lamp light).
For IML, differential diagnosis is important due to its influence on the initial therapeutic formulation as well as the result forecast and relapse after treatment.
Melasma treatments
At IML, treatment focuses on two aims:
1. Avoid melanin synthesis
2. Clarify the skin
Tyrosine activity must be controlled to avoid melanin synthesis. Therefore, depigmentation agents act by inhibiting the tyrosine’s enzymatic activity or interacting with the copper in the tyrosine prosthetic group.
Hydroquinone is one of the most widely used tyrosine inhibitors to eliminate melasmas. Its concentration as depigmentation agent should be from 2 to 6%. Kojic, azelaic and ascorbic acids are also tyrosine inhibitors, able to impede melanin synthesis.
Depigmentation agents can also behave in two different ways: interacting with the copper in the tyrosine prosthetic group or inhibiting its enzymatic activity.
The depigmentation agents that reduce enzyme activity are: cysteine, reduced glutathione, mercurials, sulfhydrylamines, paraphenylenediamine and paraaminobenzoic acid.
Another group of depigmentation agents is composed of tyrosine competitors such as fluorotyrosine, N-formyltyrosine, 3-aminotyrosine, phenylalanine and N-acetyltyrosine.
The first layers of the dermis are eliminated through superficial epidermal exfoliation. Exfoliation depends to a great degree on keratinocyte cohesion grades: the greater the grade of cohesion, the lower the grade of exfoliation and cell renewal.
Superficial epidermal exfoliation can be performed in two ways: Acting on the superficial corneocytes (from the outside in) or on the deeper corneocytes (from the inside out).
-From outside in, acting on the superficial corneocytes: through the keratinocytes that destroy the skin’s external layers, such as phenolic agents, salicylic acid, resorcinol, retinoic acid and trichloroacetic acid.
-From inside out, acting on the deeper corneocytes: through Alpha Hydroxy Acids (AHA), substances that play a part in stratum corneum peeling. Low doses of Alpha Hydroxy Acids achieve plasticity whilst high doses of AHA attain a peeling effect.
Cellular renewal can also be obtained through non-coherent and coherent light photopeeling. This consists of a light source with high-absorbtion coefficient of melanin through photocoagulation and that eliminates the most pigmented layers of skin.
The combination of all these agents and procedures allows for a more satisfactory result, tailoring for each type of melasma and skin type: melasma treatment of light skin can be much more aggressive because it does not unchain post-inflammatory repigmentations. Therefore, at IML we consider a correct analysis of skin type important as well determining the grade of aggression of the proposed treatment.
The most appropriate treatment for epidermal melasma improvement in light skins is a combination of depigmentation agents and exfoliation. The aim of peeling is to renew the epidermis and thus accelerate depigmentation and stimulate depigmentation agents to reach greater depths. IML recommends treatment associating a chemical peel with hydroquinone and isotretinoin.
After the peeling, calming lotions are used that should be applied for seven days. Their composition is high is glycerol, aloe vera, soy isoflavonoid, lactyl, lactokinone and perhydrosqualene.
Ten days after the initial application session, residual blemish removal treatment begins using a cream that should be applied over the following 3 months. Its composition includes hydrocortisones, isotretinoin and benzenodiol.
After the first three months, a gentle maintenance treatment is applied using compositions made up of kojic acid and vitamin C. Strict sun protection must be applied at all times after treatment.
The most appropriate treatment for dark skin melasma elimination is via a progressive treatment that prevents postinflamatory hyperpigmentation. IML recommends the home application of a depigmentation lotion for a fortnight before treatment consultation. This lotion is composed of ellagic acid (suppresses melanocyte tyrosine) and lactokinone.
This is followed by the application of a depigmentation peeling every five minutes to a maximum of five layers. It composition includes kojic, citric and salicylic acids as well as resorcinol and hydroquinone. The peeling should be applied for 24 before neutralising and washing. Five hours last, the application of a cream such as Eucerin Ph 5.5 is recommended.
After 24 hours, the depigmentation lotion should be reapplied. This will act as an anti-irritant and avoid repigmentation.
This type of peeling can be carried out every two or three weeks, as often as considered necessary, but it should never be applied more than a four times. If the skin’s appearance does not improve, phototherapy may be applied.
In the event of intradermal melasmas, which tend to be more resistant, the consultation treatment should be repeated. In certain cases, at IML we can reinforce the treatment with a gentle Intense Pulse Light session to eliminate dermal melanophages."