Melasma is a common disorder of cutaneous hyperpigmentation
predominantly affecting the faces of women, although not uncommon in
men. Little is known about the aetiology of melasma.
Melasma may be initiated by pregnancy and oral contraception, hence
the popular term "mask of pregnancy". Women in whom melasma develop
during pregnancy should not be treated until several months after
delivery because the dark spots often fade spontaneously. However,
avoidance of sun light exposure and daily use of a sunscreen during
pregnancy may retard the development of melasma.
Patients taking birth control pills are generally instructed to stop
taking them to increase the likelihood of successfully lightening the
pigment with depigmenting agents. At present, no data exist to suggest
that birth control pills containing low amounts of estrogen, or a
progestogen only, are less likely to produce melasma; thus, changing to
these drugs does not facilitate lightening of hyperpigmentation.
In general, melasma of recent onset respond better than long standing
cases, & the melasma of epidermal type, as determined by Wood’s
light respond faster than the mixed epidermo-dermal type.
What are the main 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 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 heritable disorder.
Sunscreens & Malasma
Sunlight is one of the major factors that influences the increased
functional state of melanocytes in melasma. Its high incidence in
tropical areas, and the recurrence of the hyperpigmentation after
sunlight exposure provide clinical evidence of the role of solar
radiation in the pathogenesis of melasma.
Because the wavelength that darken pigment extend from ultraviolet
(290-40Onm) into the visible spectrum, protection of the broadest range
should be recommended.
Sunscreens are agents that physically or chemically block the
penetration of UV light into the skin. Sunscreens usually contain more
than one agent to provide greater protection over the range of UVL
wavelengths. Products that provide protection in both UVB and UVA are
called full or broad spectrum sunscreens.
When used as directed, a sunscreen rated SPF 15 is usually adequate
for most skin types. Sunscreens with an SPF greater than 15 may be more
protective but are more expensive. They may also increase the
possibility of irritation and contact allergy because they contain
multiple sunscreen agents in higher concentrations.
Adverse effects to sunscreens are on the whole uncommon. Chemical
sunscreen agents, particularly derivatives of PABA, benzophenones,
dibenzoyimethanes and anthranilates, can occasionally cause both
allergic & photo-allergic contact dermatitis. In addition, PABA
containing preparations can stain clothing yellow and cause stinging of