What is Melasma?
Melasma is a common acquired skin disorder that presents as a bilateral, blotchy, brownish facial pigmentation.
This form of facial pigmentation was previously called chloasma, but as this derives from the Greek meaning ‘to become green’, the term melasma (brown skin) is preferred. It was also known as the ‘mask of pregnancy’.
Who gets melasma?
Melasma is more common in women than in men, with an onset typically between the ages of 20 and 40 years. Melasma is most common in people who tan easily or have naturally brown skin (Fitzpatrick skin phototypes III, IV). It is less common in people with fair skin (Fitzpatrick types I, II) or black skin (Fitzpatrick types V, VI).
What causes melasma?
The cause of melasma is complex; it has been proposed to be a photoageing disorder in genetically predisposed individuals. The pigmentation ultimately results from the overproduction of melanin by melanocytes (pigment cells); either taken up by keratinocytes (epidermal melanosis) and/or deposited in the dermis (dermal melanosis, melanophages).
Factors implicated in the development of melasma include:
- Family history — 60% report affected family members
- Sun exposure — ultraviolet and visible light promote melanin production
- Hormones — pregnancy and the use of estrogen/progesterone-containing oral contraceptives, intrauterine devices, implants, and hormone replacement therapy, are implicated in one-quarter of affected women; thyroid disorders can be associated with melasma
- Medications and scented products — new targeted therapies for cancer and perfumed soaps, toiletries, and cosmetics may cause a phototoxic reaction to trigger melasma
- Researchers are examining the roles of stem cell, neural, vascular, and local hormonal factors in promoting melanocyte activation.
What are the clinical features of melasma?
Melasma presents as bilateral, asymptomatic, light-to-dark brown macules or patches with irregular borders.
Distinct patterns include:
- Centrofacial — forehead, cheeks, nose, upper lip (sparing the philtrum); 50-80% of presentations
- Malar — cheeks, nose
- Mandibular — jawline, chin
- Erythosis pigmentosa faciei — reddened or inflamed
- Extrafacial — forearms, upper arms, shoulders in a sun-exposed distribution.
Melasma can be separated into epidermal, dermal, and mixed types, depending on the level of increased melanin in the skin.
How is melasma diagnosed?
Melasma is usually a clinical diagnosis based on the clinical appearance, it can also be diagnosed via examination with a Wood lamp and dermatoscope.
Occasionally a skin biopsy may be taken. Histology varies with the type of melasma, but typically the following features are seen:
- Melanin deposited in basal and suprabasal keratinocytes
- Highly dendritic (branched) intensely pigmented melanocytes
- Melanin within dermal melanophages
- Solar elastosis and elastic fibre fragmentation
- An increase in blood vessels.
Serial photography and severity indices such as the Melasma Area and Severity Index (MASI) or modified MASI can be used to monitor response to treatment.
What is the treatment for melasma?
A combination of measures is generally required.
- Year-round, life-long sun protection — broad-brimmed hat, broad-spectrum very high protection factor (SPF50+) sunscreen containing iron oxides, and sunsmart behavior
- Discontinue hormonal contraception if possible
Other topical agents used alone or, more commonly, in combination have included:
Many other agents are under investigation.
Chemical peels and lasers can be used with caution, but carry a risk of worsening melasma or causing post-inflammatory hyperpigmentation. Patients should be pretreated with a tyrosinase-inhibitor, such as hydroquinone.
Superficial epidermal pigment can be peeled off using alpha-hydroxy acids (AHA), such as glycolic acid, or beta-hydroxy acids (BHA), such as salicylic acid.
Microneedling, and ClearLift laser can be used for more recalcitrant melasma.
What is the outcome for melasma?
Melasma can be frustrating to treat, both for the patient and the medical practitioner. It is slow to respond to treatment, especially if it has been present for a long time.
Even in those who get a good result from treatment, pigmentation may reappear on exposure to summer sun.
The chronicity and risk for relapse with the need for lifelong sun protection should be emphasised to set realistic goals and outcomes.