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An 8-year-old Hispanic boy is brought in to the clinic by his mother, who is concerned about his pigment loss (Figure 206-1). He is starting to develop vitiligo around the eyes, and his mother wants him to be treated. The child was started on a topical steroid, and the use of narrow-band UVB was discussed if the steroid does not prove helpful. Realistic expectations of the treatments were provided to the mother and her son.
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Vitiligo is an acquired, progressive loss of pigmentation of the epidermis. The Vitiligo European Task Force defines nonsegmental vitiligo, the most common form, as "an acquired chronic pigmentation disorder characterized by white patches, often symmetrical, which usually increase in size with time, corresponding to a substantial loss of functioning epidermal and sometimes hair follicle melanocytes."1 Segmental vitiligo is defined similarly except for a unilateral distribution that may totally or partially match a dermatome; occasionally more than one segment is involved.1
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Vitiligo occurs in approximately 0.5% to 2% of the worldwide population.2,3
Nonsegmental vitiligo can occur at any age but typically develops between the ages of 10 and 30 years; segmental vitiligo develops before age 30 years with 41.3% of cases occurring before age 10 years.2
Vitiligo has equal rates in men and women.2
It occurs in all races but has the highest incidence in India, followed by Mexico and Japan.2
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ETIOLOGY AND PATHOPHYSIOLOGY
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Autoimmune or autoinflammatory disease with destruction of melanocytes. Evidence also points to melanocyte-intrinsic abnormalities that may induce an inflammatory cascade.2
Genetic factors have been observed. Susceptibility loci have been identified including a gene encoding tyrosinase, a melanocyte enzyme that catalyzes the rate-limiting steps of melanin biosynthesis.2 ApaI or the BsmI gene polymorphism are associated with risk of vitiligo in East Asian populations.4
Environmental factors, as yet unknown, may play a role; in one study, vitiligo extent was associated with birthplace, and significant regional variation was noted.5
Can trigger or worsen with illness, emotional stress, and/or skin trauma (Koebner phenomenon).
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Macules and patches of depigmentation with scalloped, well-defined borders (Figures 206-1 and 206-2).
Depigmented areas often coalesce over time to form larger areas (Figures 206-3 and 206-4).
Nonsegmental vitiligo has two identified phenotypes: early onset (before age 12 years), often associated with halo nevus (Figures 206-5) (see Chapter 168, Benign Nevi) and a familial history ...