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Psoriasis
Excimer Laser Therapy for the Treatment of Psoriasis
Rupa Pugashetti,
1
Shilpa Gattu
1
and John Koo
2
1. Medical Student, University of California, Irvine; 2. Professor of Clinical Dermatology, University of California, San Francisco School of Medicine, and
Vice Chairman, Department of Dermatology, University of California, San Francisco Medical Center
Abstract
Psoriasis vulgaris is a chronic inflammatory skin disease affecting approximately 2% of the population. Targeted ultraviolet B (UVB)
phototherapy using the 308nm excimer laser is one of the newest therapeutic options in the treatment of psoriasis. This excimer laser is
based on a xenon–chloride medium producing UV light at a 308nm wavelength. Several clinical studies have been carried out evaluating
the efficacy of the excimer laser in the treatment of plaque psoriasis. Clinical studies have demonstrated significant improvement of plaque
psoriasis and clearance following 10 or fewer treatments. Common side effects include erythema, blistering and hyperpigmentation.
Overall, the 308nm excimer laser is considered a safe and efficacious treatment for plaque psoriasis, showing great promise for the future.
Further long-term studies are warranted to evaluate its safety profile, along with its potential for the treatment of moderate to severe
plaque psoriasis and its role in combination therapy.
Keywords
Psoriasis, laser, ultraviolet B (UVB)
Disclosure: Rupa Pugashetti and Shilpa Gattu have no conflicts of interest to declare. John Koo has been a clinical researcher, consultant and speaker for Abbott, Allergan,
Amgen, Astellas, Galderma, Genentech, JSJ, Photomedex, Roche, Warner-Chilcott and Teikoku.
Received: 6 December 2008 Accepted: 19 February 2009
rpugashe@uci.edu
Psoriasis vulgaris is a chronic inflammatory skin disease affecting Targeted UVB phototherapy using the 308nm excimer laser is one of the
approximately 2% of the population, and is characterised by newest therapeutic options in the treatment of psoriasis. The excimer
erythematous, indurated, scaly plaques, which can be markedly laser is based on a xenon–chloride medium producing UV light at a
pruritic and even painful for patients. Patients with this chronic 308nm wavelength. At high fluences, this 308nm light can be used to
condition suffer from a remitting and relapsing disease course, which ablate tissue. However, when used at lower fluences in the treatment of
tends to remain active and worsen throughout a patient’s lifetime. psoriatic skin, the excimer laser acts as a form of targeted UVB
Current therapeutic options for psoriasis include topical treatments, phototherapy.
4,5
One of the advantages of localised phototherapy is that
pre-biological systemic medications such as methotrexate and light can be directed towards psoriatic plaques, thus sparing non-
cyclosporine, biological medications and phototherapy. Ultraviolet B psoriatic skin from UV light. When utilising the excimer laser, psoriatic
(UVB) phototherapy is a safe and efficacious therapeutic modality plaques can generally tolerate much higher dosages of UV light
that has been used extensively in the treatment of generalised compared with non-psoriatic skin, and therefore can require fewer
psoriasis. On the electromagnetic spectrum, UVB light ranges treatments to achieve clearance compared with conventional UVB
between the 290 and 320nm wavelengths, lying between visible and phototherapy. The minimal erythema dose (MED) constitutes the
X-ray light. More recently, narrow-band UVB (NB-UVB) phototherapy absolute limit of how aggressively conventional UVB phototherapy can
has been utilised extensively in the US, Europe, Asia and Australia. be conducted, where MED is defined as the minimal fluence of light
NB-UVB utilises a high-intensity narrow band of light from 308 to capable of producing barely perceptible erythema after 24 hours.
313nm, which helps eliminate shorter high-energy wavelengths
responsible for burning, premature ageing and increased risk of skin Clinical Efficacy
cancer. Studies from the 1980s demonstrated that the 313nm Several clinical studies have been carried out evaluating the efficacy of
wavelength allows for the lowest effective dosage of UV light, the 308nm excimer laser in the treatment of plaque psoriasis. In a pilot
causing the least erythema and with the optimal therapeutic effect in study of 10 patients with plaque psoriasis treated with excimer laser
treating psoriasis.
1,2
Traditionally, phototherapy involves the use of a three times per week, the average number of treatments needed to
UVB phototherapy box, and patients should receive phototherapy achieve complete clearance was 8.6 compared with 30.1 treatments in
sessions at least three times weekly for three months in order to a subset of patients treated with NB-UVB.
6
This pilot study suggested
induce significant clinical improvement. Furthermore, UVB the possibility that excimer laser therapy may not only be more
phototherapy is considered a safe therapeutic modality, with effective than NB-UVB in treating psoriasis, but also requires far fewer
essentially no risk of systemic side effects and little or no increased treatments to attain clearance. In another pilot study, the efficacy of the
risk of skin cancer according to published data.
3
308nm excimer laser was studied using eight different doses of UVB
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