Narrowband ultraviolet B (NB-UVB) phototherapy is currently seen as the phototherapy of choice for nonsegmental vitiligo patients.
Vitiligo is an acquired depigmentation disorder that is characterised by a chronic and progressive loss of functioning skin and/or hair follicle melanocytes. Melanocytes are found in the epidermal layer of our skin and produce melanin, the pigment that gives colour to our skin and hair. The loss of epidermal melanocytes in vitiligo leads to a loss of melanin pigment which leaves the affected area white.
The most common subtype of vitiligo, nonsegmental vitiligo, accounts for 85 to 90 percent of cases. It is believed to be caused by the immune system attacking and destroying melanocytes causing a loss of pigment and leading to the loss of colour.
NB-UVB uses specific wavelengths to activate melanin in vitiliginous lesions of the skin. This therapy is known to effectively suppress the local immune response and accelerate the maturity of melanocytes in the area around hair follicles, which act as melanocyte reservoirs, leading to repigmentation of the skin.
Although NB-UVB is one of the leading therapies for nonsegmental vitiligo, the drawbacks are numerous. Chronic effects of NB-UVB may include skin aging and photo-carcinogenesis, which may lead to skin cancer; although these long term effects are yet to be fully investigated. Treatment is required three times a week for up to 18 months and relapse is common.
- Some clinical images provided courtesy of Pearl E. Grimes, M.D.