Chemical Vitiligo: A Subset of Vitiligo.

Chemical leucoderma, an under-diagnosed common condition often mimicking idiopathic vitiligo, represents an acquired depigmentation induced by repeated exposure to specific chemical compounds in subjects with genetic susceptibility to vitiligo. This has been increasing rapidly in incidence in recent decades in developing countries like India. The term 'chemical vitiligo' was first coined by us to indicate the possible relationship between chemical leucoderma and vitiligo, which has been supported recently by other authors to designate the term 'chemical-induced vitiligo'. The largest case series showed that household chemical exposure was the major etiological factor. Causative chemicals are mostly phenolic and catecholic derivatives. Vitiligo pathogenesis is induced by genetic and environmental factors like many other autoimmune diseases. Innate immunity acts as a bridge between cellular stress and adaptive immunity. Multiple patches are commonly seen; children below 12 years are also affected in good numbers. The most common presence of confetti macules indicates these as characteristic, although not pathognomonic, of chemical leucoderma. Chemical leucoderma has been broadened into 'chemical leucoderma syndrome' with proper staging. The clinical criteria for diagnosis of chemical leucoderma have been specifically outlined. Same pathomechanism of chemical leucoderma might elucidate trigger factors and reasons for progression and chronicity in idiopathic vitiligo. Depigmentation in chemical vitiligo spreads to distant sites, in the same way as generalized idiopathic vitiligo. The study showed that chemical triggering factors played a very significant role in the induction and progression of vitiligo. Thus it should be rational to consider chemical vitiligo not as a separate entity but as a major subset of vitiligo spectrum.