Dr van Geel and collaborators have also looked at segmental vitiligo, which is characterized by a unilateral and localized distribution (Br J Dermatol. 2013; 168: 56-64). So far, the underlying mechanism is still an enigma. In order to obtain an insight into the aetiopathogenesis of segmental vitiligo the researchers compared its distribution pattern with those of dermatoses with a possible mosaic or neurogenic background.
The results showed that the distribution pattern of segmental vitiligo is not entirely similar to any other skin disease, although some mosaic skin disorders have more overlap with segmental vitiligo than others. Dr van Geel and colleagues concluded that cutaneous mosaicism may be involved in segmental vitiligo. Mosaicism is a condition in which cells within the same person have a different genetic makeup. Experts have looked at how vitiligo is classified (Ezzedine et al. Pigment Cell Melanoma Res. 2012; 25: E1-13). They concluded that segmental vitiligo be classified separately from all other forms of vitiligo and that the term ‘vitiligo’ be used as an umbrella term for all non-segmental forms of vitiligo, including ‘mixed vitiligo’ in which segmental and non-segmental vitiligo are combined and which is considered a subgroup of vitiligo. The experts recommended that disease stability be best assessed based on the stability of individual lesions rather than the overall stability of the disease as the latter is difficult to define.