Excimer Laser vs. Pulsed-Dye Laser for Psoriasis

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Summary and Comment

Excimer Laser vs. Pulsed-Dye Laser for Psoriasis

They target different aspects of the psoriasis pathway, so the PDL may be useful when the excimer laser is not.

Both the excimer laser and the pulsed-dye laser (PDL) effectively treat psoriasis, but which is more effective? In this self-controlled, prospective trial sponsored by the manufacturer of the PDL, 22 patients with plaque psoriasis received four different treatment options, one each to one of four similar plaques: twice-weekly 308-nm excimer laser (up to 12 weeks); 1 week of twice-daily 6% salicylic acid pretreatment plus one 595-nm PDL treatment monthly (4 months); salicylic acid alone (4 months); no treatment (controls).

Psoriasis Severity Index scores improved from baseline in all plaques, including controls. Mean scores improved significantly more with the excimer laser than with the PDL, salicylic acid, or no treatment. The PDL produced significantly greater PSI-score improvement than no treatment but was no better than salicylic acid alone. The best clinical response came from the excimer laser in 13 patients and from the PDL in 2 patients; in 7 patients, neither laser was better than the other. The excimer laser produced significantly better clinical response than the PDL, and the PDL produced significantly better clinical results than salicylic acid alone or no treatment. In 41% of patients, the excimer laser produced complete clearance persisting for a mean of 8 weeks; in 27% of patients, the PDL produced complete clearance, which persisted for a year in 66%. In addition, 9% of plaques treated with salicylic acid alone and 4% of control plaques cleared completely. Darker-skinned patients had poorer response than lighter-skinned patients to the lasers. Blistering, which often deferred treatment continuation, developed in 68% of excimer-treated plaques. Hyperpigmentation developed in 41% of excimer-treated plaques and in 9% of PDL-treated plaques; all but one case resolved by 1 year after treatment.

Comment: As might be expected, the UVB-based 308-nm excimer laser was more effective for psoriasis than the PDL. Although the PDL requires fewer treatments and has fewer side effects, these advantages do not outweigh its very modest benefits. The PDL might be useful in excimer-laser–resistant cases; some of these patients did not respond to the excimer but did respond to the PDL. The two systems target different parts of the psoriasis pathway, with the PDL targeting the abnormal microvasculature of psoriatic plaques.

— George J. Hruza, MD

Published in Journal Watch Dermatology December 20, 2005