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What
is Pigmentation? |
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Article by A/Prof Giam Yoke Chin
SR. Consultant Dermatologist, National Skin Centre
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Pigmentation is the color of melanin, produced by pigment
cells called melanocytes in the basal layer of the
epidermis, the most superficial layer of the skin. It is
produced by a chemical reaction, which involves an enzyme,
tyrosinase. The melanin is then distributed to the other neighboring
cells in the skin epidermis. |
What are the types of pigmentation disorders?
There are 2 main types:
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- Hyperpigmentation
- dark patches from excess production of melanin,
abnormal distribution in the skin, and even from the
effects of drugs
- Hypopigmentation
- white patches from loss or decreased production of
melanin
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What
are some of the common pigmented lesions in the skin?
In children:
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- Birthmarks
called "cafe au lait" spots (brown spots)
- Freckles
- Ota's
naevus (blue-black marks)
- Congenital
melanocytic naevus (mole)
- Speckled
lentiginous naevus (mole with pepper-like spotty
pigmentation)
- Becker's
naevus (brown patches)
- Mongolian
spots (blue marks)
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In
adults:
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- Freckles
- Pigmented
seborrhoeic warts / keratoses
- Melasma /
chloasma from hormones / pregnancy / sun damage-aging
- Post-inflammatory
hyperpigmentation from irritants / contact dermatitis /
peels
- Solar
lentigenes (brown spots from sun damage)
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What
are freckles - what can we do to remove, or prevent these?
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These
are small brown spots where the melanocytes are stimulated
by sunlight. Avoid excessive sunlight (more than 15 minutes
exposure) and use a sunblock (of SPF 25 or higher),
bleaching / fade cream, e.g. hydroquinone 2-4%, at night.
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What
is the pigment that occurs on the cheeks of pregnant women?
This is melasma or chloasma. Melasma can be seen in 3
places:
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- On the
cheeks
- Over the
"T" zone area, forehead, cheeks, upper lip
- Over the
jawline
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Some
are superficial, in the epidermis, others are deeper, both
in the epidermis and upper dermis.
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Why
do pregnant women get melasma?
The hormone, melanocyte stimulating hormone, is increased.
Women with hormonal imbalance develop melasma. |
Do men develop pigmentation on their faces?
Yes, people who are exposed to sunlight, like pilots,
golfers can get melasma. |
What is the treatment for melasma?
Avoid the sun, use sunblock. Use bleaching cream, e.g.
hydroquinone 2-4% cream. Other bleaching agents like Kojic
Acid have given good results too. If they are slow to clear,
we can try chemical peels (with alpha hydroxy acids like
glycolic acid, tricholoroacetic acid) or pigment (NdYag)
laser. |
What are pigmented seborrhoeic keratoses?
These are benign warts, which have pigmentation and develop
and grow in size with age. They can be softened with
tretinoim cream (e.g. Retin A) and scraped off (a procedure
called currettage) or lasered. |
What are pigmented moles?
They are lesions made up of melanocytes (naevus cells) which
can appear from birth ("birthmarks"), childhood,
puberty / teenage years, and during pregnancy too. |
What are the birthmarks that persist on the face?
These are "cafe au lait" spot, and Ota's naevus. |
What is the treatment?
"Cafe au lait" spots are brown spots and Ota's
naevus (blue-black patch) on cheeks are removed only by
pigment laser, the NdYag / NeodyniumYag laser which has a
specific wavelength that attacks the melanin pigment, but
does not damage the skin. If you don't want surgery, use a
camouflage cream. Not all birthmarks need treatment, as
these are not cancerous. |
Is melasma / pigmentation also a sign of aging?
Yes, in Asians, above 50 years, aging from sun damage
presents as solar lentigenes, freckles and melasma. |
What is the treatment?
Sun-damaged freckles are dark freckles that can grow to 10
times their original size with time. The treatment is a
regime of anti-aging skin care for 6 months. If you want
them removed earlier, then use tricholoroacetic acid peel or
NdYag pigment laser. For maintenance, avoid the sun and use
sunblock, SPF 25 and above. |
What is the anti-aging regime?
The regime is:
For the morning: Wash with AHA cleanser. Then use
sunblock, SPF 25 and above.
In the evening: Use tretinoin cream 0.025 - 0.1% e.g.
Retin A, Stieva A and bleaching agents containing
hydroquinone or Kojic Acid. Azaelic acid is also helpful.
Chemical peels with trichloroacetic acid (concentration of
35% and above) can also help to exfoliate the dead
cells. |
How do I select a sunblock?
There are 2 types of sunscreen: chemical and non-chemical
sunscreens.
The chemicals in most brands are oxybenzone, parsol. It is
best to buy one which covers the total range of ultra-violet
A and B rays. Those meant for prevention of sunburn cover
only UVB range.
Use non-chemical sunblocks with active ingredients like
titanium dioxide and zinc. They give a total block of UVB
and UVA. This is preferred in people with sensitive skin. |
What about white patches on the face?
These may be due to fungus, eczema (pityriasis alba), or
vitiligo from loss of pigment. |
How do we treat vitiligo on the face?
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- Use
mid-potent steroid cream. Note that strong ones cause
side effects, such as thinning of the skin.
- Use
sunblock to prevent sunburn.
- Special
treatment with phototherapy (using ultraviolet light A,
with a drug meladinine) is tried in persistent cases.
This is called PUVA.
- For those
not keen on treatments, a camouflage cream can be used.
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