Are UVB Lasers Useful for Psoriasis and Vitiligo?
Tuesday, June 05, 2007
Patients, as well as doctors, like to imagine lasers as
potentially successful and powerful. After an initial period in
which lasers were used either as a destructive tool (such as to
treat warts) or in a cosmetic field (such as depilation and
pigmentation), it's recently been proposed that lasers be used to
treat "medical conditions" such as acne, mycosis fungoides, lichen
planus, lupus erythematosus, psoriasis, and vitiligo. The excimer
laser consists of a 308-nm UVB coherent Xenon-chloride light
excimer laser that has recently been used for psoriasis and
vitiligo. Based on the first investigation with the excimer laser,
a number of new phototherapeutic devices utilizing targeted
phototherapy have been developed, such as 308-nm UVB lasers and
The aim of this Commentary is to discuss the results of some
research on the use of excimer lasers to treat psoriasis and
vitiligo, as well as to try to determine if these techniques will
indeed change our daily practice.
Phototherapy using either PUVA or narrowband UVB TL01 (311-nm)
are widely used techniques to treat psoriasis. Apart from case
reports, 15 series have been published concerning excimer laser use
for psoriasis.1 To summarize these, excimer lasers are
certainly very efficient in clearing psoriasis, giving 75% PASI
reduction in 70% of cases2 and even up to a 90% PASI
decrease in 85% of these.3
Of note, one study compared the excimer laser, a 308-nm excimer
lamp, and more interestingly, TL01 UVB, in the same
patients.4 The disease scores were not different in any
of the treatments, suggesting similar efficacy. Overall review of
these results point to three major advantages:
- The coherent UVB excimer is delivered through a device using an
articulated arm that will target only lesional skin and spare
normal skin, avoiding useless irradiation of normal skin.
- The delay to obtain clearing appears to be as short as 7-11
sessions with an excimer laser, with an average of 10 needed to
provide clearing.5 This is to be compared historically
to 25-30 sessions performed over 8 weeks for 311-nm narrowband UVB
to produce clearing.
- The cumulative dose of UVB that has been delivered -although
variable in series - appears to be lower than the cumulative dose
of narrowband UVB.
In addition to these three points, some publications have also
reported success using excimer lasers for difficult-to-treat
lesions such as scalp psoriasis, inverse psoriasis, and even
psoriasis in childhood.6,7
With these data, excimer lasers appear to be fast-acting,
skin-sparing, and UV-sparing devices. So, should we shift our
treatment from classical phototherapy to excimer lasers?
We should be cautious. Most studies have included a small number
of cases, and others have designed the clearance of designed
psoriatic plaques as the endpoint, instead of an evaluation of the
patient's global disease using a PASI score. The studies have been
done using protocols presenting several differences in the spot
size (impact diameter) and fluences. Mainly, there is variability
concerning the philosophy of the procedure, some assessing
progressive increase of fluences and others performing direct
delivery of the maximal fluence from the beginning. Some authors
began - as with classical UVB -using a suberythemogenic dose
initially followed by a stepwise increase,3,4 whereas
others delivered fixed doses closer to a classical laser
approach.8 These were indeed relying on the fact that
lesional thick plaques will tolerate a higher dose than normal
skin. Sometimes, they evaluated the minimal erythemal dose of each
The most important point remains the cutaneous side effects, as
these were rather frequent. Erythema is reported in up to 81% of
cases, and blisters are found in 63% of some series with
hyperpigmentation developing in 50-75% of cases.1,3 Pain
was typical. Some authors report these effects much more frequently
with the laser than with classical UVB phototherapy, as a
consequence of delivering intense fluence to the plaques. Some
authors and/or investigators have speculated on the fact that the
delivery of high energy in a short period of time with erythema
and/or blisters is similar to the accumulation of solar burns,
known to be the main risk factor for melanoma. There is at least a
theoretical higher risk of skin carcinogenesis.
The long-term carcinogenic risk of NB UVB phototherapy is
unclear.9 Therefore, long-term carcinogenesis studies
remain to be evaluated with UVB light sources.
Finally, one advantage of the technique - a device that spares
normal skin - is also a limit for patients who have a large area of
involvement: Those who have more than 20% of total body area
affected by psoriasis cannot practically be treated with this
technique. In localized psoriatic plaques, the excimer laser is an
interesting tool. However, there is no comparative study of
high-potency steroids with excimer lasers in these situations.
What has been said about the advantage of excimer laser for
sparing non-lesional skin is much more important concerning
vitiligo treatment. Indeed, one of the usual problems in vitiligo
patients treated with classical phototherapy is the increase in the
contrast that results from irradiation of normal skin surrounding
Excimer lasers focusing on plaques avoid this side effect, which
is poorly accepted by many patients. Studies targeting vitiligo are
still sparse - only 10 series have been published. A 57% partial
repigmentation of plaques after 4 weeks and 9% of complete
repigmentation was shown by Spencer et al.,10 whereas
85% of partial repigmentation and 20% of complete repigmentation
was demonstrated by Passeron T et al.11 In this last
paper, when excimer lasers were associated with tacrolimus, the
response was better.
Also interesting is the fact that lesions that were in
non-exposed areas did not respond to the procedure, indicating lack
of systemic effect from laser phototherapy. Of note, other later
studies did not show efficacy of tacrolimus alone in
vitiligo.11 Baltas et al. reported 4 out of 6 patients
showing 50-95% repigmentation.12 The best results of
excimer lasers are obtained after 12 weeks of treatment, apparently
best if 3 weekly sessions are delivered.13 Reported side
effects mainly include erythema, with blistering being more rare
than in psoriasis. The highest rate appears to be 20%.11
This is explained by the fact that fluences were lower than those
used in psoriasis.
Although laser excimer appears to be very promising in nearly
all these studies, one has to keep in mind that these were small
series with a non-blinded evaluation of the results. However, in
vitiligo, alternative therapies are scarce and therefore excimer
lasers appear to represent an interesting and promising strategy.
It is probable that we will use this procedure more frequently in
Excimer lasers offer a new way to improve delivery of UVB. They
can be useful in treating limited psoriasis plaques. Risk for
long-term carcinogenesis for the excimer laser must be evaluated as
for other UVB phototherapies. In contrast, it appears to be a much
more rational therapy for vitiligo.
- Passeron T, Ortonne JP. Use of the 308-nm excimer laser for
psoriasis and vitiligo. Clin Dermatol.
- Trehan M, Taylor CR. Medium-dose 308-nm excimer laser for
treatment of psoriasis. J Am Acad Dermatol.
- Gerber W, Arheilger B, Ha TA, et al. Ultraviolet B
308-nm excimer laser treatment of psoriasis: a new phototherapeutic
approach. Br J Dermatol. 2003;149(6):1250-8.
- Kollner K, Wimmershoff MB, Hintz C, et al. Comparison
of the 308-nm excimer laser and a 308-nm excimer lamp with 311-nm
narrowband ultraviolet B in the treatment of psoriasis. Br J
- Feldman SR, Mellen BG, Housman TS, et al. Efficacy of
the 308-nm excimer laser for treatment of psoriasis: results of a
multicenter study. J Am Acad Dermatol.
- Gupta SN, Taylor CR. 308-nm excimer laser for the treatment of
scalp psoriasis. Arch Dermatol. 2004;140(5):518-20.
- Pahlajani N, Katz BJ, Lozano AM, et al. Comparison of
the efficacy and safety of the 308 nm excimer laser for the
treatment of localized psoriasis in adults and in children: a pilot
study. Pediatr Dermatol. 2005;22(2):161-5.
- Asawanonda P, Anderson RR, Chang Y, et al. 308-nm
excimer laser for the treatment of psoriasis: a dose-response
study. Arch Dermatol. 2000;136(5):619-24.
- Ibbotson SH, Bilsland D, Cox NH, et al. An update and
guidance on narrowband ultraviolet B phototherapy: a British
Photodermatology Group workshop report. Br J Dermatol.
- Spencer JM, Nossa R, Ajmeri J. Treatment of vitiligo with the
308-nm excimer laser: a pilot study. J Am Acad Dermatol.
- Passeron T, Ostovari N, Zakaria W, et al. Topical
tacrolimus and the 308-nm excimer laser: a synergistic combination
for the treatment of vitiligo. Arch Dermatol.
- Baltas E, Nagy P, Bonis B, et al. Repigmentation of
localized vitiligo with the xenon chloride laser. Br J
- Hofer A, Hassan AS, Legat FJ, et al. Optimal weekly
frequency of 308-nm excimer laser treatment in vitiligo patients.
Br J Dermatol. 2005;152(5):981-5.