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UV AND VITILIGO

Vitiligo is a skin disease which has been known for several millennia. Hence, the disease was already present in the Egypt of the Pharaohs and the first Egyptian medical practitioners recommended exposure to sunlight considering its beneficial effect on the disease. More recently, the beneficial impact of natural and artificial ultraviolet radiation (UV) on the disease has been medically proven.


The purpose of the use of UV is to stimulate melanocyte growth. Melanocytes are responsible for skin color and their growth and migration is needed for repigmenting the white patches of vitiligo. Indeed, UV irradiation  produces various reactions in the skin. Some of these effects are considered as beneficial (synthesis of vitamin D, induction of a protective suntan…) whereas others are considered as harmful ("sunburn", induction of skin cancers). A medical control of UV therapy is thus needed to maximize benefit and reduce risks.


UV therapy is indicated where there is an incomplete loss of melanocytes, but its efficacy is lost in case of complete melanocyte loss. A medical staging is thus useful to assess this problem. Modalities of UV treatments are variable:


1) Natural UV light  (or heliotherapy, natural irradiation comprising UV coming from sunlight) is considered as a treatment modality. Its indication should follow medical prescription with accurate counseling on possible duration of sun exposure and accompanying sun protection. Skin exposure has to be gradually increased in time , until a slight blush appears on vitiligo patches.  Prolonged expositions should be avoided and limited and controlled exposures should be preferred. On the contrary, sunburns can aggravate vitiligo and increase the risk of skin cancer on the long term.


2) Artificial UV light can be used  even when weather conditions are not optimal (depending on season and place of residence). Different sources of artificial UV may be used such as: UV-A, UV-B, narrowband UV-B (UV-B TL01). In terms of efficacy and pigment match, recent studies indicate a slight advantage for narrow band UVB treatment. The optimal duration of treatment in responders is probably in the range of 9-12 months with twice weekly sessions. Skin cancer occuring within vitiligo patches is exceptional. However, patients with overall fair skin on long term treatment (more than 100 sessions) need to be carefully monitored and the benefit/risk of the treatment  needs to be reevaluted.


3) Different products are known to enhance the effects of UV. Psoralens are the most commonly used. These molecules are chemicals or natural, products  deriving from plants (as it is the case with bergamot). These molecules make the skin, and particularly melanocytes, more sensitive to the effects of UV. They are widely used in association with either natural (PUVA sol) or artificial  (PUVA) UV exposure. However, they should be handled with caution because they are making the skin more sensitive to UV and thus increase the risk of sunburn. Topical tacrolimus (Protopic ®) enhances the effects of UV exposure, but this association is not yet admitted by all doctors and so far considered as an off label prescription.


4) UV therapies should be avoided in case of history of skin cancer or when a total number of 200 to 250 UV sessions has been reached. Artificial exposure to UV out of a medical context should be discouraged because of the absence of control of the dose and type of UV and the related risk of skin cancer and skin aging.

 
 
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