CHICAGO A single 10 minimal erythema dose from an excimer laser can safely and effectively treat moderate to severe plaque psoriasis, Kevin D. Cooper, M.D., said at the 11th International Psoriasis Symposium sponsored by the Skin Disease Education Foundation.
The 308-nm XTRAC excimer laser treatment system (PhotoMedex, Montgomeryville, Pa.) is the first laser treatment approved for psoriasis.
It offers an obvious advantage over conventional phototherapy because it can target lesional skin with a higher initial dose of ultraviolet radiation, he said.
What hasn't been known is the optimal dose needed to treat moderate to severe psoriasis.
A minimal erythema dose (MED) of 416 has been used. But crusting of the involved skin can occur if the dose exceeds 10 MED, said Dr. Cooper, professor and chair of dermatology at Case Western Reserve University, Cleveland.
In a study that was led by his former colleague Mark Kagen, M.D., 15 patients with a mean Psoriasis Area and Severity Index (PASI) score of 18.9 and a lesional thickness of 168 μm were treated on the trunk and extremities with a single dose of 10 MED from the XTRAC excimer laser.
Patients responded rapidly at 2 and 4 weeks post treatment. On average, PASI scores were reduced from 18.9 at baseline to 8 by week 8.
"What's remarkable is that this is a single dose," Dr. Cooper said.
The response was limited to the area treated, but improvement was noted in patients of all skin types, including Fitzpatrick skin type V.
Biopsies were performed on lesions in eight patients. Lesion thickness decreased, and depletion of epidermal and dermal T cells also was observed. T-cell counts decreased from 5055 at baseline to 15 at 8 weeks post treatment.
Dr. Cooper and Dr. Kagen, now in private practice in Orlando, do not have a relevant conflict of interest.
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