Melasma or chloasma is a common type of pigmentation that commonly affects women and less commonly, men. It is most common during or after pregnancy and is often referred as the “mask of pregnancy.” People with skin phototypes IIII – IV, including Asians, Hispanics, Latinos and African-Americans are more susceptible.
Cause
The pigmentation is largely due to increased melanin production by melanocytes (melanin pigment producing cells). The melanocytes transfer the overlying keratinocyte (skin cells) causing epidermal melasma or deposit them in the dermis (deeper skin) causing dermal melasma. Why this occurs is unknown but a combination of factors may be involved:
- Genetics – a family history is found in up to 50% of women with melasma.
- Hormonal influences – Melasma commonly occurs during prengancy and in women on oral contraceptive pills and hormone replacement. Researchers have found increased oestrogen receptor expression is in melasma skin compared to unaffected skin.
- Increased vascularity – Blood vessels are often increased in melasma skin and researches have shown that vascular endothelial growth factor (VEGF) is increased in melasma skin compared to unaffected surrounding skin, suggesting that the underlying hypervascularity may play a role in the cause of melasma. Improvement of melasma after treatments that target the blood vessels further support the role of vascular factors in melasma.
Types of melasma
Melasma can be classified according to location of the pigment or distribution.
- Location
- Epidermal melasma – excess melanin is located in the epidermis
- Dermal melasma – excess melanin is in the dermis (dermal melasma).
- Mixed melasma – pigment is located in both the epidermis and dermis
- Distribution
- Centrofacial pattern – affecting the forehead, cheeks, nose and upper lips
- Malar pattern – affecting the cheeks and nose
- Mandibular pattern – affecting the jawline
Symptoms
- Light to dark brown patches with well defined margins in epidermal melasma.
- Grey-brown or blue-brown patches in dermal melasma.
- Both in mixed melasma.
- Melasma usually affects the face, especially the cheeks, forehead, nose and upper lip, and occasionally, on the forearms.
- Melasma typically darkens with sun-exposure.
Diagnosis
- Melasma is usually easily recognised by its characteristic distribution and appearance. A Wood’s light examination of the skin is useful for determining the location of the pigment and predicting the response to treatment. Wood’s light show enhancement of contrast in epidermal melasma but not in dermal melasma. Mixed melasma shows patch enhancement. Generally, a better response can be expected in epidermal melasma.
Melasma severity can be graded using the MASI (Melasma Area and Severity Index) and mMASI (modified MASI) grading scale of Pandya et al.
Complications
- Ochronosis – Is a paradoxical hyperpigmentation of the face caused prolonged use of lightening creams containing hydroquinone.
What you can do
- Reduce the triggers of melasma – sun-exposure and oral contraceptive pills.
- Apply a broad spectrum (UVA + UBV) sunscreen and wear a wide-brimmed hat.
- Use cosmetics to camouflage the pigmentation.
Outcome
- There is no cure for melasma but treatment may improve the appearance.
Treatment
- Increase skin turnover
- This results in exfoliation of the darken skin bringing to the surface clearer looking underlying skin. Products used include acids such as glycolic acid, lactic acid, malic acid, Jessner’s solution, trichloroacetic acid and retinoic acid. They also improve the penetration of lightening creams. The low pH of acids also has an inhibiting effect of the tyrosinase enzyme that is involved in melanin production.
- Lightening creams
The majority contains chemicals that directly or indirectly inhibit tyrosinase, the enzyme involved in the production of melanin or by interfering with the transfer of pigment to the surrounding keratinocytes. These are some commonly used chemicals:- Hydroquinone (often used in combination with tretinoin and a topical steroid)
- Azelaic acid
- Kojic acid
- Methimazole (antithyroid drug)
- Zinc sulfate mequinol
- Arbutin
- Ascorbic acid (acts through its antioxidant effects and interaction with copper , which is a cofactor that is important for the proper functioning of tyrosinase)
- Licorice extract
- N-acetyl glucosamine
- Niacinamide – inhibits protease-activated receptor-2 (PAR-2) resulting in a reduction of melanosome (melanin containing organelles) transfer to the surrounding keratinocytes.
- Soy extracts – works like niacinamide
- Ellagic acid
Many different combinations of the above can be used but the most has been a combination of hydroquinone, tretinoin and moderate potency topical steroid.
- Lasers and light treatments
The treatments are partially effective and need to be continued to prevent a recurrence. Hence, many patients seek alternatives such as light and laser treatments. Many types of light and laser machines have been used which in a way tells us that no one treatment is uniformly effective. This is a non-exhausting list of treatment available for patients who respond to the conventional treatments above.- Intense pulsed light (IPL) or broadband light (BBL) – IPL/BBL works better in epidermal melasma but is better suited skin phototypes skin types I – III because of the higher risk of PIH in darker skin types. The improvement could be due to the its effect on the hypervascularity of melasma as with PDL and KTP lasers below.
- Q-switched nanosecond lasers and picosecond Ruby, Alexandrite and NdYag lasers – These laser work work through their photoacoustic (vibration) effect. They are excellent for treating pigmented lesions such as freckles, lentigines and tattoos and were initially believed to have potential for treating melasma. However, Q-switched nanosecond lasers Ruby, Alexandrite and NdYag lasers may cause still cause temporary PIH or darkening of melasma. Picosecond lasers are probably safer but not witout risk from the PIH point of view. The Q-switched NdYag nanosecond laser has been used successfully for lightening melasma when used in low fluencies or energies but multiple treatments are necessary. Picosecond and low fluence Q-switched NdYag lasers are probably the safest.
- Pulsed-dye laser (PDL), KTP (potassium titanyl phosphate) and (PDL; 585 nm) and copper bromide (CuBr) lasers target the hypervascularity that may play a role in the causation of melasma. Effectuveness is uncertain and may still cause PIH.
- Non-ablative fractional lasers (NAFL) – Several wavelengths have been used, most commonly 1550nm (Erbium-Glass) and 1927nm (Thulium) laser. Fractional lasers irradiate the skin with narrow penetrating beams of light. ‘Fractional’ means that only a fraction of the entire surface is treated. However, PIH can still occur and lowering the energy and density of the beams has been suggested.
Recurrence is unfortunately common so patients need to continue maintenance light and laser treatments or use the conventional treatments mentioned earlier..