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Abstract
Vitiligo is a skin disorder characterized by the destruction
and / or inactivation of melanocytes, resulting in patches of
depigmentation.
It affects individuals of all ethnic origins with an estimated
prevalence of 0.5% -1% of the world population.
20 to 30 percent of Vitiligo patients may have a family
history of this disorder . Men and women are equally affected. It can
develop at any age. However, it begins before the age of 20 in about
half of cases.
Any area of skin can be affected. However, the most common
sites involved are the face, neck and scalp. Other common sites
include the backs of hands, front of knees, and elbows. It is often
symmetrical in that patches may appear on similar places on each arm
or leg. In the areas of the scalp that are affected, the hair too is
affected causing it to become grey or white.
Vitiligo is a multifactorial polygenic disorder with a
complex pathogenesis. It is related to both genetic and
nongenetic factors. Although several theories have been
proposed about the pathogenesis of vitiligo, the precise cause
remains unknown. Theories regarding vitiligo include autoimmune
mechanisms, cytotoxic mechanisms, an intrinsic defect of
melanocytes, oxidant-antioxidant mechanisms, and neural
mechanisms.
The pathogenesis is thought to involve an autoimmune process
directed against melanocytes. Evidence of this is derived from
histologic studies that have found an absence of melanocytes in the
affected skin.
An autoimmune process is also suggested by the concomitant
occurrence of other autoimmune diseases in patients with vitiligo.
Alterations in both cellular and humoral immunity have been reported.
Evidence supports cellular immunity as an important factor in the
development of vitiligo. CD8+ T cell predominant infiltrates have
been found in perilesional skin and CD8+ cytotoxic T cells have been
identified adjacent to disappearing melanocytes. Circulating
melanocyte specific CD8+ cytotoxic T lymphocytes have been
detected in the peripheral blood of patients with vitiligo, but it is
unconfirmed whether these T cells correlate with those found in the
skin .