Transcript Vitiligo

白 癜 风
vitiligo
Definition
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Vitiligo is a condition that causes
depigmentation of parts of the skin. It occurs
when skin pigment cells die or are unable to
function.
The incidence worldwide is less than 1%, with
some populations averaging between 2-3%
causes
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What causes vitiligo?
Vitiligo develops when cells called melanocytes (meh-lano-sites) die. These cells give our skin and hair color.
Scientists do not completely understand why these cells
die. One type of vitiligo, non-segmental vitiligo, may be an
autoimmune disease. An autoimmune disease develops
when the body mistakes a part of itself as foreign. If the
body mistakes these cells as foreigners, it will attack and
kill these cells.
Vitiligo is sometimes associated with autoimmune and
inflammatory diseases, commonly thyroid overexpression
and underexpression
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Studies suggest that the other type of
vitiligo, segmental vitiligo, has a
different cause. This type seems to
develop when something in the
body’s nervous system goes awry.
causes
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Variations in genes that are part of the immune
system or part of melanocytes have both been
associated with vitiligo
the gene TYR, which makes the skin pigment
cell (melanocyte) more susceptible to the
immune system in vitiligo, The major alleles of
TYR are associated with vitiligo, and the minor
alleles are associated with malignant melanoma
PTPN22, was associated with generalized
vitiligo (protein tyrosine phosphatase
nonreceptor-22 gene )
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A genomewide association studies
found approximately 36 independent
susceptibility loci for generalized
vitiligo. Some patients had vitiligo
alone; others had generalized vitiligo
with other autoimmune diseases.
Most loci were associated with both
forms.
Classification
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Classification attempts to quantify vitiligo
have been analyzed as being somewhat
inconsistent, while recent consensus have
agreed to a system of segmental vitiligo (SV)
and non-segmental vitiligo (NSV).
Non-segmental
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Classes of non-segmental vitiligo include the following:
Generalized Vitiligo: the most common pattern, wide and
randomly distributed areas of depigmentation
Universal Vitiligo: depigmentation encompasses most of the
body
Focal Vitiligo: one or a few scattered macules in one area,
most common in children
Acrofacial Vitiligo: fingers and periorificial areas
Mucosal Vitiligo: depigmentation of only the mucous
membranes
Segmental
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Segmental vitiligo (SV) differs in appearance,
cause and prevalence from associated
illnesses. Its treatment is different from that of
NSV. It tends to affect areas of skin that are
associated with dorsal roots from the spinal
cord and is most often unilateral. It spreads
much more rapidly than NSV and, without
treatment, it is much more stable/static in
course and is not associated with auto-immune
diseases.
Segmental vitiligo (SV)
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It tends to affect areas of
skin that are associated
with dorsal roots from
the spinal cord and is
most often unilateral.
Focal Vitiligo: one or a few scattered macules in
one area, most common in children
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Mucosal Vitiligo: depigmentation of only the
mucous membranes
Generalized Vitiligo: the most common pattern, wide and randomly
distributed areas of depigmentation
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Acrofacial Vitiligo: fingers and periorificial
areas
Universal Vitiligo:
depigmentation
encompasses most
of the body
毛发受累
Diagnosis
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A black light (also referred to as a UVA light,
Wood's lamp, or simply ultraviolet light) can
be used in the early phase of this disease for
identification and to determine effectiveness of
treatment. Skin with vitiligo, when exposed to
a black light, will glow blue. In contrast,
healthy skin will have no reaction.
Treatment
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Topical applied steroids
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There are many treatments for vitiligo with the
best evidence for applied steroids and the
combination of ultraviolet light in combination
with creams
Immune mediators
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Tentative evidence supports a role for
tacrolimus. There is tentative short term
evidence for pimecrolimus but long term data
is missing.
Phototherapy
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Exposing the skin to UVB light from UVB lamps is
the most common treatment for vitiligo.
Both UVB broadband and UVB narrowband lamps
can be used, but narrowband ultraviolet picked
around 311 nm is the choice
Ultraviolet light (UVA) treatments are normally
carried out in a hospital clinic. Psoralen and
ultraviolet A light (PUVA) treatment involves taking
a drug that increases the skin's sensitivity to
ultraviolet light, then exposing the skin to high doses
of UVA light.
excimer laser准分子激光
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Patient may sit in a light box or receive
excimer laser准分子激光treatments.
Light box used to treat widespread
vitiligo; laser used to treat small area.
Works best on the face; least effective on
hands and feet.
Effective for many patients; about 70
percent see results with excimer laser.
Skin camouflage
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In mild cases, vitiligo patches can be hidden
with makeup or other cosmetic camouflage
solutions.
Transplanting melanocytes
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a number of transplantation techniques has
been developed, including transplantation of
melanocyte precursors derived from hair
follicles.
De-pigmenting
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In cases of extensive vitiligo the option to depigment the unaffected skin with topical drugs
like monobenzone莫诺苯宗 , mequinol对甲氧
基苯酚 , or hydroquinone氢醌 may be
considered to render the skin an even colour.
The removal of all the skin pigment with
monobenzone is permanent and vigorous. Sunsafety must be adhered to for life to avoid
severe sun burn and melanomas.
Depigmentation takes about a year to complete
黑素细胞模式图
黄褐斑
chloasma
melasma
Definiton
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Melasma (also known as Chloasma faciei, or the
mask of pregnancy when present in pregnant women)
is a tan or dark skin discoloration. Although it can
affect anyone, melasma is particularly common in
women, especially pregnant women and those who are
taking oral or patch contraceptives or hormone
replacement therapy (HRT) medications.
Causes
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Melasma is thought to be the stimulation of melanocytes by the
female sex hormones estrogen and progesterone to produce more
melanin pigments when the skin is exposed to sun. Women with
a light brown skin type who are living in regions with intense
sun exposure are particularly susceptible to developing this
condition.
Genetic predisposition is also a major factor in determining
whether someone will develop melasma.
The incidence of melasma also increases in patients with thyroid
disease.
It is thought that the overproduction of melanocyte-stimulating
hormone (MSH) brought on by stress can cause outbreaks of this
condition.
Other rare causes of melasma include allergic reaction to
medications and cosmetics.
临床表现
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The symptoms of melasma are dark, irregular
well demarcated hyperpigmented macules to
patches commonly found on the upper cheek,
nose, lips, upper lip, and forehead.
These patches often develop gradually over
time.
Melasma does not cause any other symptoms
beyond the cosmetic discoloration.
Melasma is also common in pre-menopausal
women. It is thought to be enhanced by surges
in certain hormones.
Diagnosis
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Melasma is usually diagnosed visually or with
assistance of a Wood's lamp (340 - 400 nm
wavelength). Under Wood's lamp, excess melanin
in the epidermis can be distinguished from that of
the dermis.
Treatment
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The discoloration usually disappears
spontaneously over a period of several
months after giving birth or stopping the oral
contraceptives or hormone replacement
therapy.
Treatments are often ineffective as it comes
back with continued exposure to the sun.
Treatments to hasten the fading of the
discolored patches include:
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Topical depigmenting agents, such as
hydroquinone (HQ) either in over-the-counter
(2%) or prescription (4%) strength. HQ is a
chemical that inhibits tyrosinase, an enzyme
involved in the production of melanin.
Tretinoin, an acid that increases skin cell
(keratinocyte) turnover. This treatment cannot
be used during pregnancy.
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Azelaic acid (20%), thought to decrease the activity
of melanocytes.
Chemical peels.
Microdermabrasion to dermabrasion (light to deep).
Galvanic or ultrasound facials with a combination of
a topical crème/gel. Either in an aesthetician's office
or as a home massager unit.
Laser and IPL
Oral Tranexamic acid has shown to provide rapid and
sustained lightening in melasma by decreasing
melanogenesis in epidermal melanocytes
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In all of these treatments the effects are gradual and a
strict avoidance of sunlight is required. The use of
broad-spectrum sunscreens with physical blockers,
such as titanium dioxide and zinc dioxide is preferred
over that with only chemical blockers. This is because
UV-A, UV-B and visible lights are all capable of
stimulating pigment production.
Patients should avoid other precipitants including
hormonal triggers.
Cosmetic camouflage can also be used to hide
melasma.