Skin hyperpigmention disorders affect about 30% of the population. Melasma (also called chloasma and mask of pregnancy), post-inflamatory hyperpigmented, lentigos (known as liver spots), and severe freckles are among the most frequent pigmentary disorders of human skin.
What is melasma?
Melasma is a chronic skin hyperpigmentation disorder that results from the hyperactivity of melanocytes. It produces symmetrical, blotchy, brownish facial pigmented patches.
Melasma can be epidermal, dermal or mixed. Epidermal melasma is brownish in colour and results from an excessive amount of pigment in the superficial part of the skin, the epidermis. Dermal melasma is rather grayish in colour. In this type, melanin pigments are also present in the deep part of the skin, i.e. in the dermis. The mixed type of melasma has both epidermal and dermal components.
Melasma is a complex chronic skin disorder that affects the social life of many patients
Who develops melasma?
Melasma commonly arises in healthy, non-pregnant adults. Melasma is more common in women than in men; only 1-in-4 to 1-in-20 affected individuals are male, depending on the population studied. It generally starts between the age of 20 and 40 years, but it can begin in childhood or not until middle age. Melasma is more common in people that tan well or have naturally brown skin (Fitzpatrick skin types 3 and 4) compared with those who have fair skin (skin types 1 and 2) or black skin (skin types 5 or 6).
How do we develop melasma?
The pigmentation is due to overproduction of melanin by the pigment cells, melanocytes, which is taken up by the keratinocytes (epidermal melanosis) and/or deposited in the dermis (dermal melanosis, melanophages).
Although it is also called the mask of pregnancy, many melasma patients develop this skin disease without any relation to pregnancy and the disease also affects men. Contraceptive pills, sun exposure and certain medications such as phenytoin can induce melasma. There is a genetic predisposition to melasma, with at least one-third of patients reporting other family members to be affected. However, in most cases, the cause of melasma is complex and remains unclear.
Melasma is due to the overproduction of melanin by the pigment cells, the melanocytes
What are the clinical features of melasma?
Melasma presents as macules (freckle-like spots) and larger flat brown patches. There are several distinct patterns:
- Centrofacial pattern: forehead, cheeks, nose and upper lips
- Malar pattern: cheeks and nose
- Lateral cheek pattern
- Mandibular pattern: jawline
- Reddened or inflamed forms of melasma (also called erythrosis pigmentosa faciei)
- Poikiloderma of Civatte: reddened, photo-aging changes seen on the sides of the neck, mostly affecting patients older than 50 years
- Brachial type of melasma affecting shoulders and upper arms (also called acquired brachial cutaneous dyschromatosis).
The clinical feature varies upon the type of melasma:
|Type of melasma||Clinical features|
|Epidermal||Well-defined border; dark brown colour; appears more obvious under black light; responds well to treatment|
|Dermal||Ill-defined border; Light brown or bluish in colour; Unchanged under black light; Responds poorly to treatment|
|Mixed||Combination of bluish, light and dark brown patches; Mixed pattern seen under black light; Partial improvement with treatment|
How Melasma is treated today?
Melasma can be very slow to respond to treatment, especially if it has been present for a long time. Treatment may result in irritant contact dermatitis in patients with sensitive skin, and this can result in post-inflammatory pigmentation.
Several depigmenting molecules have been used for the treatment of melasma. The most effective treatments have been based on products that contain hydroquinone. Hydroquinone, after being applied onto the skin, is absorbed by the melanocytes and is metabolized within the (hyper-functioning) melanocytes to produce a toxic radical (quinone) that causes the abnormal melanocyte to die. This causes the melasma area to become normal in colour, as hydroquinone has little or no effect on the normally functioning melanocytes.
Although hydroquinone is considered to be the most effective treatment for hyperpigmentation, its use has become more and more restricted in recent years due to reports on the cancer-producing effect of this agent. Hydroquinone has thus been banned in several countries including European countries and Japan.
A substitute to hydroquinone?
After the hydroquinone ban, several products have been developed and put on the market for the treatment of hyperpigmentation. These products contain depigmenting agents such as kojic acid, azelaic acid, arbutin, glabridin, and more recently developed molecules, such as 4-butyl resorcinol or 4-ethyl-phenyl resorcinol. However, experience has shown that the majority of these molecules and fractional laser treatments are far less effective than hydroquinone as hyperpigmentation treatments.
This leaves health-authorities, clinicians and patients seeking for a true substitute.