Objectives: At present, laser therapy of port-wine stains (PWS) using the long-pulsed dye laser (LPDL) is accepted as the optimal approach, because the ideal thermal relaxation time for the vessels in PWS is actually 1-10 msec, not 450 microseconds. In the clinical setting, however, the degree of efficacy of the LPDL, which is dependent on pulse duration and energy fluence, has not been determined, especially in dark-skinned patients with PWS. The purpose of this study is to elucidate the efficient fluence(s) and pulse duration(s) of the LPDL for treatment of PWS with less adverse effects. Materials and Methods: 178 Japanese patients with PWS were recruited for this study. All the patients were dark-skinned with skin phototype III (n=103) and IV (n=75), and were treated with the LPDL with a pulse duration ranged from 1.5 to 10 msec and a fluence ranged from 9 to 15 J/cm2, and a spot size of 7 mm). Patients were called back to the hospital within a week after their initial laser treatment. Two clinicians who were not familiar with the treatment method looked for evidence of complications including purpura, blister, and ulcer formation, and the Akaike’s information criterion (AIC) was used to analyze the influence of pulse duration and energy fluence used on purpura formation. Results: Of the 178 patients, 108 developed purpura, 6 had blister, but none had ulcer formation. The lowest fluences causing purpura formation that was seen more than 50% were 10 J/cm2 with pulse duration of 1.5 msec, 12 J/cm2 with pulse duration of 3 msec, 13 J/cm2 with pulse duration of 6 msec, and 13 J/cm2 with pulse duration of 10 msec. The fluence and pulse duration thresholds were 12.5 J/cm2 and 1.65 msec, respectively. The AIC score was –15.72 for the fluence and –9.87 for the pulse duration. Conclusions: Dark-skinned patients are less responsive to laser treatment with higher rate of complications such as temporary purpura and blister formation or permanent pigmentary changes. Purpura formation, which shows exclusive effect of the laser on the skin, remains a concern to patients, but does not result in pigmentary disorder in contrast to blister formation. Our results suggest that use of high fluence and short pulse duration is associated with efficient treatment of PWS with less adverse effects in dark-skinned patients. Additionally, use of skin cooling device will further increase clinical efficacy and decrease complication rate.
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