Summary During the 2011 International Pigment Cell Conference (IPCC), the Vitiligo European Taskforce (VETF) convened a consensus conference on issues of global importance for vitiligo clinical research. As suggested by an international panel of experts, the conference focused on four topics: classification and nomenclature; definition of stable disease; definition of Koebner’s phenomenon (KP); and ‘autoimmune vitiligo’. These topics were discussed in seven working groups representing different geographical regions. A consensus emerged 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. Further, the conference recommends 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 precisely and reliably. The conference also endorsed the classification of KP for vitiligo as proposed by the VETF (history based, clinical observation based, or experimentally induced). Lastly, the conference agreed that ‘autoimmune vitiligo’ should not be used as a separate classification as published evidence indicates that the pathophysiology of all forms of vitiligo likely involves autoimmune or inflammatory mechanisms.

The aetiopathogenic mechanisms of vitiligo are still poorly understood, and this has held back progress in diagnosis and treatment. Up until now, treatment guidelines have existed at national levels, but no common European viewpoint has emerged. This guideline for the treatment of segmental and nonsegmental vitiligo has been developed by the members of the Vitiligo European Task Force and other colleagues. It summarizes evidence-based and expert-based recommendations (S1 level)

Common generalized vitiligo is an acquired depigmenting disorder characterized by a chronic and progressive loss of melanocytes from the epidermis and follicular reservoir. However, the mechanism of melanocyte disappearance has never been clearly understood, and the intervention of cellular and humoral autoimmune phenomena as primary events remains unproven. In this review, is discussed the data supporting the major theories of vitiligo, namely melanocyte destruction (autoimmune, neural and impaired redox status) and melanocyte inhibition or defective adhesion. Based on recent morphologic findings in vivo supporting a chronic detachment and transepidermal loss of melanocytes in common generalized vitiligo, a new theory is suggested proposing melanocytorrhagy as the primary defect underlying melanocyte loss, integrating most of the possible triggering/precipitating/ enhancing effects of other known factors.

No abstract

Vitiligo is the most common depigmenting disorder resulting from the loss of melanocytes from the basal epidermal layer. The pathogenesis of the disease is likely multifactorial and involves autoimmune causes, as well as oxidative and mechanical stress. It is important to identify early events in vitiligo to clarify pathogenesis, improve diagnosis, and inform therapy. Here, we show that E-cadherin (Ecad), which mediates the adhesion between melanocytes and keratinocytes in the epidermis, is absent from or discontinuously distributed across melanocyte membranes of vitiligo patients long before clinical lesions appear. This abnormality is associated with the detachment of the melanocytes from the basal to the suprabasal layers in the epidermis. Using human epidermal reconstructed skin and mouse models with normal or defective Ecad expression in melanocytes, we demonstrated that Ecad is required for melanocyte adhesiveness to the basal layer under oxidative and mechanical stress, establishing a link between silent/preclinical, cell-autonomous defects in vitiligo melanocytes and known environmental stressors accelerating disease expression. Our results implicate a primary predisposing skin defect affecting melanocyte adhesiveness that, under stress conditions, leads to disappearance of melanocytes and clinical vitiligo. Melanocyte adhesiveness is thus a potential target for therapy aiming at disease stabilization.

Detachment and transepidermal elimination of melanocytes following minor mechanical trauma in non lesional vitiligo skin is probably the cause of depigmentation occurring in the isomorphic response (Koebner phenomenon). We propose that transepidermal elimination of melanocytes in vitiligo should be regarded as a possible mechanism of chronic loss of pigment cells, perhaps previously damaged by another process.

No abstract

Summary Koebner’s phenomenon (KP) has been observed in a number of skin diseases, including vitiligo. Its clinical significance in vitiligo with respect to disease activity and course is still debatable, while its relevance for surgical techniques has been demonstrated in some reports. We present a literature review on the currently known facts about KP in vitiligo, including details of clinical, experimental, and histopathological changes. The consensus view is that there are still no methods to define and assess KP in vitiligo. A new classification is proposed to allow an evaluation of KP in daily practice or in experimental studies. However, many unanswered questions still remain after redefining KP in patients with vitiligo. Active research focusing on KP in vitiligo may not only provide unexpected clues in the pathogenesis of vitiligo but also help to tailor novel therapies against this chronic and often psychologically devastating skin disease.