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Vitiligo is a common acquired disorder
characterized by well-marginated milky white spots resulting from loss of
melanocytes. Vitiligo is associated with risks of ocular abnormalities and
some autoimmune disorders. In Indian and some other cultures, this innocuous
disease has been associated with social stigma since ancient times.
Confusion with leprosy is partly responsible for this.
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ETIOLOGY & PATHOGENESIS |
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Epidemiological studies suggest that vitiligo
or a susceptibility to the disease may be inherited and about one fourth
to one third of patients have family members affected with the disease. A
multifactorial pattern of inheritance is revealed in most studies.
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Three possible mechanisms that may cause
destruction of melanocytes, the pigment producing cells of the skin, has
been suggested by different workers.
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The autoimmune hypothesis
originated from the observation that vitiligo is associated with some
autoimmune diseases. Both cellular and humoral factors responsible for
autoimmune damage to melanocytes have been demonstrated.
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The autocytotoxic or self-destruct
hypothesis suggests that some toxic molecules produced during the
biosynthesis of melanin are responsible for melanocyte damage in
susceptible individuals.
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The neural hypothesis
postulates that neurochemicals liberated from nerve endings are toxic to
melanocytes.
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The varied clinical and laboratory findings
,however, indicate that multiple mechanisms may be responsible for the
causation of vitiligo in an individual.
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CLINICAL FEATURES |
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Vitiligo affects all races with an average
frequency of 1 to 2 per cent of the population. Both sexes are affected
equally and the disease may develop at any age. The peak age of onset in
most series was between 10 and 30 years. Stressful life events or
physical trauma can often precipitate the onset of disease.
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The typical macule of vitiligo is easily
recognized by well-circumscribed milky white spots of varying sizes
without any other discernable surface change of the skin. The hairs on
the patch may turn gray. There may be a single spot or numerous white
macules distributed all over the body. With passage of time, the macules
may enlarge and coalesce to produce extensive pigment loss. The lesions
are symptomless.
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Vitiligo lesions may result from ‘Koebner
phenomenon’ i.e., appearance of new lesions at sites of non-specific
trauma such as abrasion, surgical scars, severe sunburn or inflammatory
skin diseases like psoriasis or eczema.
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According to the extent of involvement and
pattern of distribution, vitiligo is clinically categorized into focal,
segmental, generalized, acrofacial, and universal types.
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Focal vitiligo is an isolated macule
or a few macules in a localized non-dermatomal distribution.
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Segmental vitiligo is characterized
by macules in a unilateral dermatomal distribution. This type of disease
usually pursues a stable course.
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Generalized vitiligo is the most
common type showing macules in a generalized widespread distribution.
There is often striking symmetry of affection and involvement of
extensor surfaces. Face (particularly around the orifices), neck, bony
prominences of hands, legs; axillae and mucosal surfaces are
particularly affected.
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Acrofacial vitiligo affects distal
end of fingers and facial orifices in circumferential pattern.
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Universal Vitiligo implies loss of
pigment over the entire body surface area with only isolated islands of
normal pigmentation remaining.
Associated
diseases:
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Patients with vitiligo have an
increased risk of developing autoimmune diseases like thyroid diseases,
Addison's disease, pernicious anaemia and insulin-dependent diabetes
mellitus. Auto antibodies against other organs may be detected in the
absence of clinical evidence of the diseases. Premature graying of hair
and alopecia areata are important cutaneous associations in some
patients.
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The pigment epithelium of retina and
choroid are developmentally derived from the neural crest, the cutaneous
melanocytes originate from the same embryonic structure. They may share
the susceptibility to damage in vitiligo; iris and retinal pigmentary
anomalies in the absence of ophthalmologic complaints may be detected in
a proportion of the patients. Iritis may be found in a small number of
patients.
Psychosocial
impact of vitiligo :
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Although vitiligo by itself is asymptomatic
and does not cause any physical discomfort or disability, it may be
associated with devastating psychological and social consequences. Since
a person's appearance is a major determinant of his/her personality
traits, vitiligo, by causing cosmetic blemishes can have major impact on
personality.
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Feeling of stress and embarrassment on
social contacts, lack of confidence and lowered self esteem may be
detrimental to the patients, particularly when the spots are on
visible area of the body.
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The psychological impact can have serious
implications in deeply pigmented races such as Indians, in whom the
contrast between the normally dark skin and the white lesions can be
marked.
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DIFFERENTIAL DIAGNOSIS |
- Post-inflammatory hypo- or depigmention
- Nevus depigmentosus
- Pityriasis versicolor
- Pityriasis alba
- Leprosy
- Chemical leukoderma
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COURSE AND PROGNOSIS |
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The common generalized vitiligo usually
pursues a course of slow progression with enlargement of existing macules
and gradual appearance of fresh spots. Quite often, after an initial phase
of progression , the lesions remain relatively stable for varying periods
of time only to be followed by accelerated spread, sometimes there may be
very rapid spread leading to extensive loss of pigmentation within a short
span of time. In an individual case the course however is unpredictable.
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In comparison with .the aforesaid, segmental
vitiligo tends to have a very stable course. Following appearance of
lesions in a dermatomal distribution, the lesions usually remain localized
to the area of affection.
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Spontaneous repigmentation may be observed in
a proportion of patients particularly in lesions on sun-exposed areas.
However, the extent of spontaneous healing is seldom cosmetically
significant.
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TREATMENT |
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There are several options for the treatment
of vitiligo. The commonest modality of treatment is systemic or topical
PUVA therapy (Psoralen + Ultraviolet A), which consists of use of psoralen
compounds followed by exposure to UV radiation in the 320 to 400nm range
(Ultraviolet A or UVA) . Corticosteroids are also used in the management
of vitiligo. Multiple surgical modalities are also available for selected
patients. In universal vitiligo, depigmenting the remaining islands of
normal skin may be the only cosmetically acceptable option.
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Repigmentation usually occurs around the
hair follicles, which is achieved by stimulation and migration of
follicular melanocytes. Spread of pigmentation from the margin of the
macules can also occur.
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Whatever the mode of therapy, patient
education and reassurance is of paramount importance. Explanation of the
benign nature of the disease and appropriate counselling and psychological
support is needed in all patients.
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Topical steroids are effective in the
management of disease limited to small area. Lesions on face and neck
respond better than other parts or the body. Hydrocortisone is the topical
agent of choice. More potent steroids can also be used intermittently.
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PUVA therapy: The use of photoactive
substances collectively called psoralens, in conjunction with exposure to
long wave ultraviolet radiation (UVA) either from artificial sources or by
sun-exposure remains the mainstay of management of vitiligo. The precise
mechanisms of action of PUVA in vitiligo remain speculative, but their
main actions involve proliferation and migration of melanocytes and
enhanced enzymatic activity for biosynthesis of melanin.
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The therapeutic agents used are mainly
8methoxypsoralen (8-MOP) and trimethyl psoralen (TMP). Psoralens should
ideally be used under supervision using artificial source of UV radiation.
Since the equipment for UV delivery is not universally available, use of
solar UV radiation by sun-exposure is the next best alternative. This
modality of therapy is called PUVASOL therapy.
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Topical PUVA/PUVASOL involves painting the
area with a weak solution of 8-MOP and exposing the area to UVA, following
which the area is thoroughly washed off with soap and water. Patients with
limited involvement (less than 10% body surface area) are best suited for
this mode of therapy. The commercially available solutions should be
diluted (e.g. 1:50 or more in alcohol) to avoid severe phototoxic
reaction. The concentration maybe increased later depending on the
response. Initially, the lesions should be exposed to sun for a few
minutes, the exposure time being increased gradually.
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Oral PUVA/PUVASOL is used in patients
with extensive vitiligo. Two hours after ingesting 0.6mg/kg of 8-MOP,
patients are exposed to artificial sources of PUVA 2 to 3 times a week.
TMP is preferable for PUVASOL therapy. The best time for sun-exposure is
10 AM. to 2 PM. Sun-exposure is initially limited to 10 minutes. After
that a gradual increase in exposure time is allowed based on the response
(erythema and tenderness). Up to 80% of patients will experience induction
of pigmentation, less than 20% of patients have total repigmentation and
30% to 40% of patients can expect to have only a partial response to
treatment. Vitiligo on lip, palms and soles, finger tips, bony
prominences, and periorificial areas respond very poorly. Psoralen-induced
repigmentation may remain stable for many years. New lesions however may
develop while on PUVA therapy. These may repigment on continued therapy.
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The potential side effects of PUVA therapy
include phototoxicity, nausea, gastric discomfort, pruritus, fatigue,
cataracts, pigmented lesions and possible carcinogenicity. PUVA therapy is
best avoided in children below the age of 12. It is contraindicated in
pregnancy and lactation, photosensitivity disorders or cataracts.
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Patients should be instructed to have
ophthalmologic examination yearly and to wear UV absorbing goggles for 24
hours following the treatment.
Surgical treatment:
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When topical steroids or PUVA therapy fails
to repigment, surgical treatment may be undertaken. Surgical therapies are
time-consuming and can be considered in inactive, non-progressive disease
only. They are best suited for segmental and localized vitiligo. Areas
such as fingers, ankles, forehead and hairlines tend to show poor results.
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Autologous minigrafting.
Multiple, small punch biopsy specimens are taken from an appropriate donor
site and at the recipient treatment site where the biopsy sites are
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separated by 4 to 5mm of vitiliginous skin.
The donor specimens are placed on the recipient defects and the grafts are
sealed. Centrifugal pigmentation spreads from the recipient site.
Concomitant PUVA therapy may help pigment spread. This procedure may give
excellent results in segmental vitiligo. A cobblestone appearance or
scarring may occur at the treatment site.
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Epidermal grafting
involves formation of blisters at the donor and recipient sites by the use
of a suction apparatus and removing the roof of the blisters. The roof of
the blisters of the donor sites are placed on the denuded areas on the
recipient sites and dressings are applied on the donor as well as the
recipient sites.
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Transplantation of in vitro-cultured
melanocytes on denuded areas of vitiliginous recipient
sites has also been successful in producing cosmetically acceptable
repigmentation of vitiligo.
Depigmentation:
In patients with extensive vitiligo,
depigmenting the remaining islands of normal skin may be more cosmetically
acceptable. To achieve this, monobenzyl ether of hydroquinone in a
concentration of 20% is applied twice a day on the pigmented skin. It may
take months to establish depigmentation, which is usually permanent.
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