Melasma
/Melasma is a commonly acquired increase of pigmentation that occurs
exclusively in sun-exposed areas. Brownish in color, it is exacerbated
by sun exposure, pregnancy, oral contraceptives, and certain
anti-epilepsy drugs.
Melasma is reasonably common, especially in women of child-bearing age.
However, up to 10% of cases have been reported in males. While all
races are affected, there is a prominence among Latinos and Asians.
Melasma is more apparent during and after periods of sun exposure and
less obvoius in winter months, when sun exposure is lacking.
Melasma presents itself in one of the three usually symetrical facial
patterns. The most common is a centrofacial pattern involving the
cheeks, forehead, upper lip, nose, and chin. Less common are the malar
pattern, involving the cheeks and nose, and the mandibular pattern,
involvong the ramus of the mandible (the side of the cheeks and
jawline). Melasma also occurs on the forearms, but this is rare.
What is the Difference between Dermal and Epidermal Melasma?
Every case of melasma starts off in the epidermis, where melanocytes
are actively producing pigment. A normal case of melasma can turn into
dermal melasma if skin becomes over-irritated and inflamed. When this
happens, it causes a temporary split between the dermis and epidermis.
During this time, hyperpigmented cells can drop from the epidermis into
the dermis. Once in the dermis, these cells become very resistant to
topical treatment. This is one reason why it is so important to avoid
aggressiveness in the treatment of melasma.
What are the Causes of Melasma?
Melasma has been considered to arise from pregnancy, oral
contraceptives, endocrine dysfunction, genetic factors, medications,
nutitional deficiency, hepatic dysfunction, and other factors. The
majority of cases appear to be related to pregancy or oral
contraceptives. The infrequency of melasma in postmenopausal women on
estrogen replacement suggests that estrogen alone is not the cause. In
more recent experience, combination treatment using estrogen plus
progestational agents is being used in postmenopausal women, and
melasma is being observed in some of these older women who did not have
melasma during their pregnancies. Sun exposure would appear to be a
stimulating factor in predisposed individuals. Although a few cases
within families have been describe, melasma should not be considered a
heriditary disorder.
Treatments for Melasma
Hydroquinone is the most
popular, and is also the most effective topical hypopigmenting agent.
Hydroquinone works by inhibiting the conversion of tyrosine to melanin,
inhibiting the formation of melanosomes and increase the degredation of
melanosomes, and by inhibiting the DNA and RNA synthesis of melanocytes.
As a result, only cells with active tyrosinase activity are affected by
HQ. Active tyrosinase activity is only found in epidermal melanocytes.
In dermal melanin, tyrosinase activity is not present; therefore dermal
melasma is resistant to hydroquinone. The efficacy of hydroquinone is
related to the concentration of the preparation. Preparations with a
hydroquinone concentration of 2% or less do not require a prescription,
but are much less effective than prescription counterparts and are only
recommended for maintenance therapy. Concentrations of 5%-10%
hydroquinone are very effective, but can be irritating. The chemical
stability of hydroquinone formulations is important because HQ is
easily oxidized and loses potency. HQ formulations should be kept in
small, dark bottle of no larger than 1 ounce and should be used within
30 days.
The lightening effect of hydroquinone can be enhanced by combining it
with other agents such as alpha hydroxy acids and tretinoin.
Side effects of hydroquinone include irritation, possible allergic
reactions, nail discoloration, postinflammatory hyperpigmentation (dark
spots), and temporary lightening or depigmentation of treated and
surrounding skin. These side effects are temporary and will resolve
when the HQ formula is no longer used. There is one other possible, and
rare, permanent side effect known as ochronosis. Ochronosis is a
permanent grey or blue-black discoloration occuring in very
dark-skinned or African American patients after prolonged treatment
with an HQ formula with an HQ concentration greater than 3%.
Tretinoin (Retin-A, Renova) is
another widely used therapy for melasma. Tretinoin does have a
lightening effect on melasma and can be used alone or in conjunction
with HQ. Tretinoin works by promoting the rapid loss of pigment via
increased epidermopoiesis, easing penetration of HQ into the skin, and
preventing HQ oxidation..
Kojic Acid is derived from a
variety of different fungi and organic substances (such as soy and
mushrooms). The current belief is that kojic acid suppresses free
tyrosinase by the chelation of the copper ion. Kojic Acid has been
known to cause contact allergies in a small number of people. Kojic
Acid has an ester that may be more effective and less irritating than
kojic acid itself. One therapeutic ester is kojic dipalmitate. The
exact mechanism of action of kojic dipalmitate is not known except that
it is a tyrosinase inhibitor.
Azelaic Acid is a dicarboxylic
acid that is derived from cereal grains such as wheat, rye, and barley.
The depigmenting action of azelaic acid is related to its inhibition of
tyrosinase, the enzyme necessary for melanogenesis. The clinical
efficacy of an azelaic acid 20% with glycolic acid 15% cream was
compared to a 4% hydroquinone cream. The results revealed equivalent
reduction of the pigmentation in both groups, with a slightly greater
irritancy rating with the group that used the combination of the
azelaic acid and glycolic acid.
Azelaic acid may take several months to be effective as a depigmenting
agent. Hydroquinone should be discontinued after prolonged use due to a
plateau of efficacy and to avoid the possibility of ochronosis. Azelaic
acid would make a good alternative to hydroquinone for continued
therapy. A small percentage of patients may, however, experience some
itching or burning.
Arbutin is an extract of a bearberry plant and derivative of
hydroquinone. It can inhibit the formation of tyrosinase while also
preventing oxidation of hydroquinone. This is a popular treatment in
Japan, where hydroquinone is unavailable.
N-acetyl-4-cysteaminylphenol is
a depigmenting agent that acts on functioning melanocytes with minimal
side effects. It has shown good results in a 4% formulation, and is
more stable and less irritating than hydroquinone. In one study, 75% of
the cases showed improvement.
Licorice also helps inhibit tyrosinase activity and can be used with HQ or tretinoin.
Vitamin C can be combined with
other melasma treatments for enhanced results. It can fade melasma from
a dark black to light tan while also providing additional protection
from the sun. In one study, 55% of the cases showed improvement after 5
months on a 10% formulation.
Mandelic Acid, an alpha hydroxy
acid derived from the bitter almond, has been shown to have a
lightening effect on melasma. Its most important aspect is its ability
to fade dermal melasma, which has long been known to be resistant to
topical therapies. The majority of melasma cases are a combination of
dermal and epidermal melasma. The best results are gained on this type
of melasma when mandelic acid is combined with a hydroquinone or other
bleaching formula. It is also effective when used alone and is a great
alternative for those who are sensitive to hydroquinone or for those
who hyperpigment easily.
Sunscreen is the most important
factor for successful treatment. Without daily use of opaque sunscreen,
treatment will fail. A broad-spectrum formulation with an SPF over 30
plus cover up is adequate. Look for sunscreens that contain PARSOL 1789
or avobenzone, Zinc Oxide, and/or Titanium Dioxide. Make sure the
formula is sweatproof if you plan on being in the sun for long hours.
Normally up to 2 months are required to begin to initiate response and
up to 1 year to complete the process. Once epidermal melasma is cleared
and is no longer apparent with Wood's lamp examination, the
hydroquinone and tretinoin should be discontinued. However, the opaque
sunscreen should be continued through at least one summer season to
reduce the risk of recurrence. Often, melasma will slowly resolve
following childbirth or upon discontinued use of oral contraceptives.