Koebner phenomenon and Halo Naevi

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The Koebner phenomenon (KP) refers to the development of vitiligo within an area of skin that has been damaged by localised, often mild trauma eg an injury.  Dr N van Geel and colleagues of Ghent have looked at this phenomenon (see British Journal of Dermatology 2012;167:1017-24.). They developed a new assessment method for KP, taking into account both the history and clinical examination of people with vitiligo; this seems to be a useful and valuable tool for assessing KP in daily practice.

The results support the hypothesis that KP may be used to assess and predict the course of vitiligo.

Halo naevi are common moles with a white ring around them, showing the sort of pigment loss that is seen in vitiligo. Dr van Geel and researchers have looked at how these moles can present together with vitiligo or separately (British Journal of Dermatology 2011; 164: 743-9). Their results support the theory that halo naevi can represent a distinct condition but in a subset of people, the occurrence of halo naevi may be an initiating factor in the pathogenesis of vitiligo.