Narrowband UVB: Shedding Light on Vitiligo Treatment
It can be challenging to know the right protocol to treat vitiligo. Phototherapy is an effective and well-tolerated treatment option.1 In this article, we shed light on phototherapy treatments for vitiligo and discuss expected outcomes for various patients.
Vitiligo is a photo responsive autoimmune dermatosis in which melanocytes are killed, causing a lack of melanin and subsequent hypopigmentation. As one of the more challenging diseases to treat with phototherapy, vitiligo often requires lengthy courses of treatment. Any technique optimization to expedite repigmentation should be considered and patients should be counseled to expect several months of treatment before abandoning phototherapy.
As in the case of many other photo responsive diseases, 300-320nm UVB from either targeted or a Narrowband UVB source is typically tried first over PUVA therapy (Psoralen and UVA light). Although an exact mechanism of action is not known, Narrowband UVB light most likely changes the expression of various cytokines, reducing the immune system’s attack on the melanocytes, while also cleaving proopiomelanocortin into various melanocyte growth promoting peptides, most notably α-melanocyte-stimulating hormone.
There appears to be two phenotypes of vitiligo patients: approximately two-thirds of patients will photo adapt to Narrowband UVB relatively quickly, much like a psoriasis patient, with the remaining one-third tolerating much lower dose increments without erythema. Unfortunately, at this time, there does not appear to be any distinguishing traits to tell the two groups apart, which gives a serious protocol problem to clinicians. A conservative protocol starting at 200mJ with 50mJ increments will work in all patients, but will give unnecessarily slow results and greater cumulative UV exposure to two-thirds of patients. Alternatively, a psoriasis-like protocol using 15% dose increases will be significantly more effective for most patients, but will cause at least one episode of erythema (before reducing increases) for the other one-third of patients. At this present moment, there is not an absolute answer as to which protocol to use, so practitioner habit and patient preference should guide selection.
Typically the fastest responding patients, on an aggressive (15% increase/3x week) protocol of Narrowband UVB will see significant repigmentation within 20 treatments, but a trial period of 3 months is typical. If a patient hasn’t seen repigmentation within 30-40 treatments, it is likely, they are not a good candidate for Narrowband UVB phototherapy. On the other hand, if they are responding well, it is common to continue with effective treatment for years.
There are some reports that the speed of repigmentation is proportional to the duration of the diseases, with faster responses in patients with relatively short histories of vitiligo.
1 Narrowband ultraviolet B is a useful and well-tolerated treatment for vitiligo Scherschun, Lubomira et al. Journal of the American Academy of Dermatology, Volume 44 , Issue 6 , 999 – 1003.