#melasma #chloasma

Melasma is a very troublesome condition especially in pigmented skin. It is important to note that only superficial located pigment can improve, but not the pigment located deeper in the dermis. Examination with Wood’s lamp (360nm, blue light) is a plus, although it may be less reliable in phototypes IV and above because the pigmentation is invariably seen in the dermis.

Whitenning creams act by four mechanisms:

• by killing the melanocyte (the cell that produces melanin): hydroquinone, resorcinol.

• by inhibiting melanin production: methimazole, kojic acid, azelaic acid, arbutin.

• by inhibiting the transfer of the pigment to the epidermis: soy bean extracts.

• by increasing celular turnover (shedding of dead cells): retinol, retinaldehyde, retinoic acid.

 Before beginning treatment it is useful to determine the depth where the pigment is located: 1) epidermal (superficial): easier to achieve good results; 
2) dermal (deep): more challenging to achieve results; 
3) mixed: more effective results on epidermal pigment.

Treating melasma

How to decide if a depigmenting cream is effective? On a practical point of view, it is wise to check if studies on a depigmenting agent are done at the three levels: 1) in vitro: cultured melanocytes where it is easiest to make pigment vanish; 2) in vivo: the cream is usually tried on hairless mice, and 3) in vivo in humans: to demonstrate proven efficacy and safety.

Existing depigmenting creams on the market:

• New:
  • deoxyarbutin
  • nicotinamide
  • methimazole
  • soybean extracts

• Old:
• hydroquinone
• azelaic acid, kojic acid, arbutin: studies done in vitro only.

First line treatment:

Hydroquinone: side effects are allergic contact dermatitis in 5% of cases. Ochronosis remains a rarity in reality and is more likely if concentration is more than 10%, if use is long-term and if skin phototype is IV or more. No skin cancer has ever been reported (Squamous Cell Carcinoma, Basal Cell Carcinoma, Malignant Melanoma). 

Retinoids: retinaldehyde has been shown to be twice as effective in depigmentation as retinïc acid but with a less irritating side-effect.

PRACTICALLY speaking the treatment is done in two phases:

• Intensive phase
  • duration: 3 months
  • Hydroquinone 3-5% combined with ascorbic acid 3-5% in alternate nights. Note that the association is only stable about three months.
  • Retinaldehyde 0.05% to apply in alternate nights.
• Maintenance phase
  • Hydroquinone to apply once a week at night.
  • Retinaldehyde 0.05% to apply every other day at night.

• It is important to apply the cream on the whole area where the skin lesion is and not on the lesion itself because a hypopigmented halo can form (except in skin phototypes I and II).

Aditional recommendations:

• For temporary improvement: alpha-hydroxy acid peels (30-70%)
• If topicals fail to be effective , IPL and Pigment lasers (NDYAG 1064) may me tried, but only performed by a medical doctor with knowledge of skin conditions as there is a risk the colour could get worse.
• All treatments must be accompanied by a broad spectrum sunscreen.

This advice is just for informational purposes and does not replace therapeutic judgement done by a skin doctor.