Abstract: 【Abstract】 Objective To evaluate the efficacy and safety of 532-nm picosecond laser in the treatment of early-stage facial seborrheic keratosis. Methods A total of 95 patients with early-stage facial seborrheic keratosis were prospectively enrolled from the Department of Dermatology, General Hospital of Ningxia Medical University between December 2020 and September 2022. All the patients received a session of 532-nm picosecond laser treatment, and were followed up for 6 months. A 4-point scale was used to evaluate the overall improvement of skin lesions for assessing the clinical efficacy. A VISIA skin detector to quantitatively determine the characteristic counts, absolute scores, and percentiles of brown spots before and after treatment, and the paired sample t-test was used to compare the quantitative indicators of brown spots before and after treatment. The patients′ pain grades were evaluated, and adverse reactions were recorded. Results All the 95 patients with early-stage facial seborrheic keratosis received a session of 532-nm picosecond laser treatment, and completed a 6-month follow-up. All the patients achieved over 25% regression of skin lesions in the treatment area, of whom 10 received mild improvement, 17 received favorable improvement, and 68 received marked improvement, with the response rate being 89.47% （85/95）. The results of the VISIA skin detector showed that the characteristic counts （195.19 ± 51.06） and absolute scores （28.80 ± 6.20 points） of brown spots significantly decreased and the percentiles of brown spots （38.48% ± 10.80%） significantly increased at 6 months after treatment compared with the corresponding baseline indicators （211.48 ± 50.94, 35.16 ± 6.84 points, 30.61% ± 10.27%, t = 12.73, 16.90, -15.73, all P < 0.001, respectively）. All the patients experienced varying degrees of pain during the treatment, with the pain scores being 2 - 6 （3.64 ± 1.67） points, but all of them could tolerate the pain and completed the treatment. Temporary postinflammatory hyperpigmentation and hypopigmentation occurred in 9 （9.47%） and 4 （4.21%） patients respectively, which recovered to normal in color during the 6-month follow-up. Conclusion The 532-nm picosecond laser was safe and effective for the treatment of early-stage facial seborrheic keratosis.

Key words: Keratosis, seborrheic, Laser therapy, Treatment outcome, Safety, 532-nm picosecond laser