Abstract: 【Abstract】 Objective To investigate the clinical efficacy of 595-nm pulsed dye laser （PDL） in the treatment of port-wine stains （PWS） in infants and toddlers. Methods A retrospective analysis was conducted based on clinical data from 155 infants and toddlers with PWS treated with 595-nm PDL at West China Hospital of Sichuan University from January 2013 to October 2023, and the efficacy was evaluated according to pre- and post-treatment photographs. The children were grouped according to gender, age, lesion color, lesion area, lesion sites, and number of treatment sessions, separately, and the differences were analyzed between different groups. Further analysis was conducted to determine factors affecting efficacy of PDL for PWS. Adverse reactions after treatment were recorded. The Mann-Whitney U test and Kruskal-Wallis H test were used to analyze unidirectional ordered R × C contingency table data, the Bonferroni approach was used for multiple comparisons, and multivariate ordered logistic regression analysis was performed for multifactorial analysis. Results After the treatment with 595-nm PDL, 135 infants and toddlers with PWS showed good response, with an overall response rate of 87.1%. Univariate analysis indicated that the efficacy was associated with the lesion area （P = 0.016） and the number of treatment sessions （P < 0.001）, but not with age （P = 0.340）, gender （P = 0.164）, lesion color （P = 0.530）, or lesion sites （P = 0.077）, and the smaller the lesion area, the more the treatment sessions, the better the therapeutic effect. Multivariate ordered logistic regression analysis further confirmed the correlations of efficacy with lesion area （P = 0.010） and number of treatment sessions （P < 0.001）. Adverse reactions occurred in 5 （3.2%） cases of PWS, including 2 （1.3%） of hypopigmentation, 2 （1.3%） of hyperpigmentation, and 1 （0.6%） of scar formation. Conclusion The 595-nm PDL was safe and effective for the treatment of PWS in infants and toddlers with few adverse reactions, making it a reliable therapeutic option.

Key words: Port-wine stain, Lasers, dye, Child, Treatment outcome, Adverse reaction