Treating vitiligo and psoriasis with the excimer laser

Psoriasis affects 1% to 3% of the population worldwide.1 Research is continually being conducted on this disease, and medicine continues to make new discoveries regarding the immunologic pathogenesis. In January 2008, Strober and colleagues reported that visceral adiposity and an elevated body mass index are associated with elevations of tumor necrosis factor   and interleukin-6, which contribute to insulin resistance and atherosclerosis.2 These researchers found that psoriasis and obesity are associated with high systemic and local levels of tumor necrosis factor.2 Their theory is that psoriatic and adipocytic inflammation potentiate each other. It is thus possible that psoriasis and obesity may derive from shared genetic defects. Strober also found that obese patients with moderate to severe psoriasis have high C-reactive protein levels, suggesting they are at risk for cardiovascular disease. We know that patients with psoriasis are at an increased risk for metabolic syndrome, cardiac disease, depression, and lymphoma. Gelfand and colleagues found that a patient with mild psoriasis has a 1.5-fold increased risk for MI.3 In this same study, patients with severe psoriasis had a 7-fold increased risk for MI.3 These findings suggest that we should no longer think of psoriasis as merely a skin disease but rather consider it to be a complicated immunologic process that affects all other organ systems, including the cardiovascular system.

A NEW APPROACH TO PSORIASIS

Traditional phototherapy, beginning with broadband ultraviolet B (UVB) therapy, has been used for many years to treat psoriasis. This therapy is effective and typically requires a minimum of 25 treatments.4 A more advanced version of phototherapy called narrowband UVB therapy uses the most effective wavelengths in the treatment of psoriasis: 300 to 313 nanometer (nm). Narrowband UVB therapy is widely viewed as safer and more effective than broadband UVB therapy. However, both treatments have disadvantages. These include the requirement to visit the office for treatment 3 times a week, an inconvenience for most patients, and an increased risk of skin cancer if the patient has more normal skin than psoriatic skin that is exposed to the UVB therapy. Neither method is typically utilized in patients with localized disease, making an effective mode of treatment for localized disease increasingly necessary.

By using an intense beam of laser light on a smaller area of affected skin (2 2-cm spot size), the XTRAC 308-nm excimer laser effectively and safely treats localized, recalcitrant plaques of psoriasis and vitiligo. Because the focused laser beam avoids unaffected skin, much higher doses of UVB can be administered. Doses as high as 6 times the minimal erythema dose (MED) for normal skin were tolerated during the treatment of psoriatic plaques.5

Of patients in a recent study who received the required 10 excimer laser treatments, 72% (66 of 92 patients) achieved at least 75% clearing in an average of 6.2 treatments and 35% (28 of 80) achieved at least 90% clearing in an average of 7.5 treatments.6 Two patients achieved 90% clearing in one treatment.6

Excimer laser treatments have many advantages over traditional phototherapy. Fewer treatments yield a lower overall cumulative dose. The therapy is effective for thick plaques on elbows, knees, and—most importantly—the scalp. Before this option was available, essentially no good treatments were available for the scalp area except topical medications, which are difficult to manage for both the patient and provider. In fact, excimer laser treatment has been the most exciting benefit for the majority of patients whose scalp is affected. These patients often have lived for years with stubborn, scaly plaques and now are experiencing relief for the first time. Finally, this therapy provides a substantial benefit to patients who respond well to traditional therapies but have one remaining recalcitrant plaque. And studies show that remission times are similar to those of traditional phototherapy.7

Most patients experience no pain or discomfort with the excimer laser treatment, nor any of the stinging or burning associated with other laser therapies. One of the largest studies to date found that 63 of 124 patients (50.8%) experienced erythema as a side effect.6 To the provider, erythema is a positive sign and typically indicates an overall good response to the treatment. Some patients also experience blisters and hyperpigmentation. If a blister occurs, the dose is reduced by one MED (14%-33%) and the affected area is not treated at the subsequent visit.

LASER THERAPY FOR VITILIGO

In our office, many patients report being told that “nothing” will help their vitiligo to improve. Providers in the United States often do not fully understand the far-reaching ramifications for some patients with vitiligo. For example, for patients of Middle Eastern and Indian background, vitiligo may carry a stigma similar to that of leprosy. Patients fear becoming social outcasts who are not able to marry or find a job. The disease can be devastating to patients and their families.

Many dermatology offices continue to utilize traditional phototherapy, topical corticosteroids, and topical calcineurin inhibitors in the treatment of vitiligo. Unfortunately, these treatments can have a number of side effects, including nonmelanoma skin cancer (phototherapy) and atrophy, striae, tachyphylaxis, hirsutism, and steroid acne (topical corticosteroids). PAs in primary care and family practice settings can now tell their patients with vitiligo that the excimer laser is a safe, effective treatment for their condition.

Traditional therapies for vitiligo require months of treatment and yield often disappointing results. One pilot study for the excimer laser in the treatment of vitiligo showed that 57% of patients studied had partial to complete repigmentation after only 6 of 12 treatments over a 2- to 4-week period.8 Another study looked specifically at the effectiveness of treatment with the excimer laser according to body site. In the 24 patients studied, repigmentation started after a mean of 13 treatments in lesions located on the face, trunk, arm, and leg and after a mean of 22 treatments of lesions on the elbows, wrist, dorsal hand, dorsal foot, and knee.9 The therapeutic benefit of the excimer laser can be affected by the location of the vitiliginous lesions, meaning areas that have been historically difficult to treat with traditional therapy will respond more slowly to this innovative treatment.

The treatment protocol for vitiligo is similar to that for psoriasis in that 2 to 3 treatments per week are generally recommended. Patients with vitiligo can have hope that they will see results more quickly with excimer laser therapy than with traditional phototherapy.

¦ Improvements on traditional therapies, such as the XTRAC excimer laser, are making it easier to treat psoriasis and vitiligo safely and effectively.

¦ The 308-nm excimer laser is an ideal modality for historically difficult to treat areas, including elbows, knees, and the scalp, in patients with psoriasis.

¦ Other advantages of the excimer laser for psoriasis include the need for fewer treatments, yielding a lower overall cumulative dose; the ability to treat single recalcitrant plaques; and remission times similar to those seen with traditional phototherapy.

¦ Traditional therapies for vitiligo require months of treatment and yield often disappointing results. Patients with vitiligo can have hope that they will see results more quickly with the excimer laser than with traditional phototherapy.

FINAL COMMENTS

Most major insurance companies will reimburse for treatment with the excimer laser under CPT codes based on the amount of surface area treated on each patient. The software within the excimer laser precisely calculates the area treated for the provider. The laser costs approximately $85,000 to $90,000 to purchase. JAAPA

Bethany Grubb works at Aftergut Dermatology in Dallas, Texas, and is the president of the Society of Dermatology Physician Assistants. She has indicated no relationships to disclose relating to the content of this article.

REFERENCES

1. Greaves MW, Weinstein GD. Treatment of psoriasis. N Engl J Med. 1995;332(9):581-588.

2. Strober BS, Perelman RO, Teller C, et al. C-reactive protein levels in patients with psoriasis and psoriatic arthritis: effects of etanercept therapy [abstract]. J Am Acad Dermatol. 2008;58: AB122. (Abstract P2623).

3. Gelfand JM, Neimann AL, Shin DB, et al. Risk of myocardial infarction in patients with psoriasis. JAMA. 2006;296(14):1735-1741.

4. Adrian RM, Parrish JS, Momtaz-T K, Karlin MJ. Outpatient phototherapy for psoriasis. Arch Dermatol. 1981;117(10):623-626.

5. Asawanonda P, Anderson RR, Chang Y, Taylor CR. 308-nm excimer laser for the treatment of psoriasis: a dose-response study. Arch Dermatol. 2000;136(5):619-624.

6. 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 of Dermatol. 2002;46(6):900-906.

7. Trehan M, Taylor CR. Medium-dose 308-nm excimer laser for the treatment of psoriasis. J Am Acad Dermatol. 2002;47(5):701-708.

8. Spencer JM. Treatment of vitiligo with the 308-nm excimer laser: a pilot study. J Am Acad Dermatol. 2002;46(5):727-731.

9. Hofer A. The efficacy of excimer laser for vitiligo (308 nm) at different body sites. J Eur Acad Dermatol Venereol. 2006;20(5):558-564.