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Facts about the skin from DermNet New Zealand Trust. Topic index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z



Melasma

What is melasma?

Melasma is a chronic skin disorder that results in symmetrical, blotchy, brownish facial pigmentation. It can lead to considerable embarrassment and distress.

This form of facial pigmentation is sometimes called chloasma, but as this means green skin, the term melasma (brown skin) is preferred.

Chloasma Chloasma Chloasma
Melasma / chloasma

More images of melasma ...

What causes melasma?

The cause of melasma is complex. 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). There is a genetic predisposition to melasma, with at least one-third of patients reporting other family members to be affected. In most people melasma is a chronic disorder.

Known triggers for melisma include:

Melasma commonly arises in healthy, non-pregnant adults and persists for decades. Exposure to ultraviolet radiation (UVR) deepens the pigmentation because it activates the melanocytes to produce more melanin.

Research is attempting to pinpoint the roles of stem cell, neural, vascular and local hormonal factors in promoting melanocyte activation.

Who gets melasma?

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).

What are the clinical features of melasma?

Melasma presents as macules (freckle-like spots) and larger flat brown patches.These are found on both sides of the face and have an irregular border. There are several distinct patterns.

Melasma is sometimes separated into epidermal (skin surface), dermal (deeper) and mixed types. A Wood lamp that emits black light (UVA1) may be used to identify the depth of the pigment.

Type of melasma Clinical features
Epidermal
  • Well-defined border
  • Dark brown colour
  • Appears more obvious under black light
  • Responds well to treatment
Dermal
  • The most common type
  • 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 is the diagnosis of melasma made?

The characteristic appearance of melasma means diagnosis is usually straightforward and made clinically. Other disorders that may be considered include:

Occasionally, skin biopsy may be performed to make or confirm the diagnosis of melasma. Histology varies with the type of melasma. But some degree of each of the following features is usually found.

The extent and severity of melasma can be described using the Melasma Area and Severity Index (MASI).

What is the treatment of melasma?

Melasma can be very slow to respond to treatment. Treatment may result in irritant contact dermatitis in patients with sensitive skin, and this can result in postinflammatory pigmentation.

Generally a combination of the following measures is helpful.

General measures

Topical therapy

Tyrosinase inhibitors are the mainstay of treatment. The aim is to prevent new pigment formation by inhibiting formation of melanin by the melanocytes.

Other active compounds used for melasma include:

Superficial or epidermal pigment can be peeled off. Peeling can also allow tyrosinase inhibitors to penetrate more effectively.

The most successful formulation has been a combination of hydroquinone, tretinoin, and moderate potency topical steroid. This has been found to result in improvement or clearance in up to 60–80% of those treated. Many other combinations of topical agents are in common use, as they are more effective than any one alone. However, these products are often expensive.

Oral treatment of melasma

Oral medications for melasma are under investigation, including tranexamic acid (a prescription medicine in New Zealand). None can be recommended at this time.

Devices used to treat melasma

The ideal treatment for melasma would destroy the pigment, while leaving the cells alone. Unfortunately, this is hard to achieve. Machines can be used to remove epidermal pigmentation but with caution—over-treatment may cause postinflammatory pigmentation. Patients should be pretreated with a tyrosinase inhibitor (see above).

Fractional lasers and intense pulsed light (IPL) appear to be the most suitable options. Several treatments may be necessary and postinflammatory hyperpigmentation may complicate recovery.

Carbon dioxide or erbium:YAG resurfacing lasers, pigment lasers (Q-switched ruby and Alexandrite devices) and mechanical dermabrasion and microdermabrasion should be used with caution in the treatment of melasma.

What is the outcome of treatment of melasma?

Results take time and the above measures are rarely completely successful.

Unfortunately, even in those that get a good result from treatment, pigmentation may reappear on exposure to summer sun and/or because of hormonal factors. New topical and oral agents are being studied and offer hope for effective treatments in the future.

Related information

References:

 

DermNetNZ:

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Author: A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Updated September 2014.

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If you have any concerns with your skin or its treatment, see a dermatologist for advice.