How does phototherapy for vitiligo work?

Hello,

Phototherapy is a large umbrella term for the use of ultraviolet (UV) light for the purpose of treating skin conditions. There are a number of different applications for phototherapy (especially in different skin conditions) and it stands as one of the bread-and-butter techniques for treatment of vitiligo beyond the use of topicals.

In vitiligo, the patient's skin has undergone an autoimmune-mediated destruction of pigment-producing cells. The role of phototherapy is to:

1. stabilise the skin condition and
2. stimulate the remaining melanocytes for purposes of repigmentation.

UV light is absorbed by the outer layers of the skin by specific components of the skin. It sets off a number of chemical signalling pathways which results in a modulation of cell activity. The end result is that it helps to stabilise the skin and has a local immunosuppressive/anti-inflammatory effect which slows/stops the further spread of vitiligo.

In addition, the UV rays will be absorbed by the pigment-producing cells on the skin. For some vitiligo patients, there are melanocyte stem cell stores within the hair follicle which can be stimulated to multiply and begin the repigmentation process. Early stages of repigmentation can appear like below, with the small spots of pigment growing outwards from each individual hair follicle.

Phototherapy is most often undertaken as a long term treatment with varying outcomes largely dependent on the regularity and compliance to sessions. Most often, patients are recommended to undergo sessions 2-3 times a week and will need to wait for a few months before they can expect to see results.

While the term phototherapy is all-encompassing, for the purposes of vitiligo there are differences in types of UV light used. For patients considering treatment, it would be good to understand what is the type of UV light being used, be it:

• UVA,
• UVA in conjunction with a photosensitising agent (P-UVA),
• broad band UVB (BB UVB), or
• narrow band UVB (NB UVB).

Hope this helps to address your question!

Best regards

Dr Chris Lim