Introduction to laser treatment of psoriasis

Psoriasis is a common and socio-psychologically disabling skin ailment. It is chronic, recurring and its acute and localized variations are difficult to manage. Among the various treatment options, laser therapy was developed in order to ensure a patient-tolerant and prolonged clearance alternative for this disease. Hence, the 308-nm excimer laser was used to treat psoriasis in 1997.

Laser psoriasis therapy was not only the first application of laser in the field of dermatology but was also the first to be approved by the US Food and and Drug Administration. It has advantages in selectively treating only specific infected areas and hence sparing the surrounding healthy skin; good tolerance in psoriasis vulgaris and vitiligo; it has technical characteristics that allows the use of high fluencies that are beneficial in case of dense plaques of psoriasis; its ‘articulated arm’ allows access to tough to treat areas like folds and mucosa; lastly its monochromatic wavelength of 308 nm ensures photobiological effects supposedly more effective than NB-UVB. Its main disadvantages include a lack of along-term follow-up regimen, defined and best parameters for treatment, vagueness about maintenance doses, limited spot size that cannot treat large surfaces and high purchase and maintenance costs of the apparatus used.

Here is an overview of the various psoriasis laser therapies:

Psoriasis vulgaris

Comparative studies conducted since the introduction of 308-nm excimer laser in 1997 for treatment of psoriasis vulgaris have come up with contradictory reports. While some studies showed improvement in conditions faster than the NB-UVB, others reported the same degree of effectiveness. Similar effectiveness was also found when compared to the 308-nm lamp therapy. Studies comparing 308-nm excimer laser with topical steroids or calcipotriol are also not comprehensive.

Initial studies regarding the procedure included higher fluencies, since selectivity is a major advantage of this treatment, hence ensuring minimum damage of surrounding healthy tissues. The outcome was satisfactory in terms of clearance of lesions and number of treatment sessions needed. However, there are transient side effects such as serious burns, blisters accompanied with considerable pain and long-standing ones even as threatening as skin cancers. Hence use of such high fluencies and doses has been discouraged.

Studies conducted later on involved lesser fluencies with gradual increase in doses and around 10 sessions spaced out in two to three weekly ones. The outcome was encouraging; with a 90% clearance rate and lesser side effects like hyperpigmentation, erythema and rare blisters. However, very few follow-up studies have been conducted and among them the average recurrence rate is after 4 months from end of treatment.

Inverse psoriasis

The reports of treatment of this kind of psoriasis with the 308-nm excimer laser are based on pilot studies or case reports. Though, inverse psoriasis is difficult to cure, some studies have reported good results with a 308-nm excimer laser. Conventional phototherapy is not too effective since it fails to reach the folds. Topical agents on the other hand are not encouraged due to side effects such as infection or inflammation.

Genital psoriasis

Based on pilot studies, 308-nm excimer laser has reportedly proved effective in the treatment of acute genital psoriasis. It took 16 sessions to achieve healing and the condition reappeared 3 months following the end of treatment.

Palmoplantar psoriasis

Treatment of this kind of psoriasis is generally of two suggested approaches. The first is a combined therapy of a 308-nm excimer laser and acitretin. The other substitutes localized psoralen–UV-A instead if acitretin and is the lesser preferred one.

Scalp psoriasis

The 308-nm excimer laser has been the mainstay in the treatment of acute scalp psoriasis as well. It has proved effective in conditions that could not be managed with topical steroids. Such cases involved sessions in the range of 15 to 23 and the 308-nm excimer laser was accompanied with an air blower apparatus. The best part is that there was no reappearance of the condition till as long as 10 weeks after the end of treatment.