Catecholamines Level in Urine and Serum in Stable Non-segmental Vitiligo Patients Before and After Excimer Light

Despite much research, the etiology of vitiligo and the causes of melanocyte death are not clear. Conventionally, there have been three hypotheses to explain the pathogenesis of vitiligo: neural, immune and self-destructive, but none can completely explain the disease and are probably interrelated.

From therapeutic and prognostic viewpoint, vitiligo is broadly classified in two major subtypes, segmental vitiligo (SV) including focal lesions confined to a segment of the body that does not progress towards generalized disease; and non-segmental vitiligo (NSV) which comprises all generalized usually symmetrical forms, including acrofacial vitiligo.

The increased release of catecholamines (CA) from the autonomic nerve endings in the micro-environment of melanocytes in the affected skin areas might be involved in the aetiopathogenesis of vitiligo through two main mechanisms: a direct cytotoxic action of CA and/or their o-diphenol catabolites and an indirect action, skin and mucosa arterioles possess receptors, activation of which by CA discharge may cause a severe vasoconstriction, leading to epidermal and dermal hypoxia with excessive production of toxic oxyradicals generated by different pathways.In both cases, a genetic predisposition due to insufficient radical scavengers in the affected areas should be taken into account.

First line of non-surgical therapy includes topical corticosteroid therapy and phototherapy (solar exposition, Psoralen + UVA (PUVA), narrowband UVB (NB-UVB). (8-10). The NB-UVB is now considered as the best treatment for extensive vitiligo vulgaris due to its relatively good efficacy and excellent tolerance .

Contrary to the majority of laser devices, the 308-nm excimer laser is not a ''destructive'' form of therapy but induces photobiological effects similar to selective UVB phototherapy (311-312 nm).As for UVB phototherapy, it could be judged that the efficiency of the 308-nm excimer laser in treating vitiligo depends on immunomodulatory effects (induction of the secretion of cytokines, T-lymphocytes apoptosis) and stimulation of melanocyte migration and proliferation from the niche located in hair follicles. The 308-nm excimer laser allows a selective treatment of the lesions. This device has already shown interesting results in post-resurfacing leukoderma.