755-nm picosecond laser plus topical 20% azelaic acid compared to topical 20% azelaic acid alone for the treatment of melasma: a randomized, split-face and controlled trial.

Purpose: Melasma remains a refractory skin condition that needs to be actively explored. Azelaic acid has been used for decades as a topical agent to improve melasma through multiple mechanisms, however, there is a lack of research on its combination with laser therapy. This study evaluated the effectiveness of isolated treatment with topical 20% azelaic acid and its combination with 755-nm picosecond laser in facial melasma patients.

Methods: A randomized, evaluator-blinded, controlled study was conducted on 30 subjects with facial melasma in a single center from October 2021 to April 2022. All subjects received topical 20% azelaic acid cream (AA) for 24 weeks, and after 4 weeks, a hemiface was randomly assigned to receive 755-nm picosecond (PS) laser therapy once every 4 weeks for 3 treatments. Treatment efficacy was determined by mMASI score evaluations, dermoscopic assessment, reflectance confocal microscopy (RCM) assessments and patient's satisfaction assessments (PSA).

Results: Treatment with 20% azelaic acid, with or without picosecond laser therapy, significantly reduced the hemi-mMASI score (P < 0.0001) and resulted in higher patient satisfaction. Improvements in dermoscopic and RCM assessments were observed in both sides of the face over time, with no difference between the two sides. RCM exhibited better dentritic cell improvement in the combined treatment side. No patients had serious adverse effects at the end of treatment or during the follow-up period.

Conclusion: The additional use of picosecond laser therapy showed no clinical difference except for subtle differences detected by RCM assessments.The study was registered in the Chinese Clinical Trial Registry (ChiCTR2100051294; 18 September 2021).