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Author: A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand, 1997. Updated September 2014.
Melasma is a chronic skin disorder that results in symmetrical, blotchy, brownish facial pigmentation. Melasma can also affect the arms and back. 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.
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).
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 deposited in the dermis (dermal melanosis, melanophages). 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 melasma include:
Melasma commonly arises in healthy, non-pregnant adults. Lifelong sun exposure causes deposition of pigment within the dermis, and this often persists long-term. 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.
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, dermal, and mixed types. A Wood lamp that emits black light (UVA1) may be used to identify the depth of the pigment.
The characteristic appearance of melasma means the diagnosis is usually straightforward and made clinically. Other disorders that may be considered instead of melasma or as well as melasma include:
Occasionally, a 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).
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.
Generally, a combination of the following measures is helpful.
Tyrosinase inhibitors are the mainstay of treatment. The aim is to prevent new pigment formation by inhibiting the formation of melanin by the melanocytes.
Other active compounds used for melasma include:
The superficial or epidermal pigment can be peeled off. Peeling can also allow tyrosinase inhibitors to penetrate more effectively. These must be done carefully as peels may also induce post-inflammatory pigmentation.
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 a single agent. However, these products are often expensive.
Oral medications for melasma are under investigation, including tranexamic acid. Tranexamic acid is a lysine analogue that inhibits plasmin and is usually used orally to stop bleeding. It reduces the production of prostaglandins, the precursors of tyrosine. In a low dose, tranexamic acid has been reported to be effective and safe in the treatment of melasma, providing patients have been carefully selected and are at low risk of thromboembolic disease.
Glutathione is also under investigation as a systemic skin whitening agent but has potentially severe adverse effects.
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, Q-switched Nd:YAG lasers, picosecond lasers and intense pulsed light (IPL) appear to be the most suitable options. Several treatments may be necessary, and post-inflammatory 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.
Results take time, and the above measures are rarely entirely successful.
Unfortunately, even in those that get a good result from treatment, pigmentation may reappear on exposure to summer sun and because of hormonal and endogenous factors. New topical and oral agents are being studied and offer hope for effective treatments in the future.
Del Rosario E, Florez-Pollack S, Zapata L Jr et al. Randomized, placebo-controlled, double-blind study of oral tranexamic acid in the treatment of moderate to severe melasma. J
Am Acad Dermatol. 2017 Oct 4. pii: S0190-9622(17)32458-1. doi: 10.1016/j.jaad.2017.09.053. [Epub ahead of print] PubMed PMID: 28987494. Journal.
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