Postoperative Risk Assessment of Post-inflammatory Hyperpigmentation and the Efficacy of Delayed Prevention Following 532 nm Q-switched Nd:YAG Laser Treatment of Solar Lentigines: a Randomized Controlled Study

Background: Although post-inflammatory hyperpigmentation (PIH) is a common adverse event following laser procedures, studies evaluating its risk remain limited.

Objective: To analyze PIH risk after 532 nm Q-switched Nd:YAG laser (QSNYL) treatment for solar lentigines and examine the efficacy of triple combination cream (TCC) for its prevention.

Methods: In this single center, investigator-blinded, randomized controlled study, participants with solar lentigo either received TCC or emollient from 2 weeks post-QSNYL treatment. The occurrence of PIH was determined by three independent and blinded dermatologists. skin measurements and sun exposure questionnaires were examined to evaluate the risk of PIH.

Results: A total of 28 patients with 67 solar lentigines were included in the analysis. In the control group, PIH occurred in 55.3% of the lesions. Risk factors for the occurrence of PIH were the increased erythema at weeks 2 (OR, 1.32;  = 0.035) and outdoor activity during 1-5 pm (OR, 8.10;  = 0.038). Treatment with TCC from 2 weeks post-QSNYL treatment significantly decreased the incidence of PIH (31.0% vs. 55.3%,  = 0.048).

Conclusion: Post-laser erythema and outdoor activity at the daytime are prognostic factors for the occurrence of PIH. Administering TCC could be considered for the prevention of PIH in high-risk patients.