Comparative study of treatment efficacy and the incidence of post-inflammatory hyperpigmentation with different degrees of irradiation using two different quality-switched lasers for removing solar lentigines on Asian skin

• Published in: Journal of the European Academy of Dermatology and Venereology 2013-03, Vol.27 (3), p.307-312
• Main Authors: Negishi, K., Akita, H., Tanaka, S., Yokoyama, Y., Wakamatsu, S., Matsunaga, K.
• Format: Article
• Language: English
• Subjects: Humans; Incidence; Inflammation - etiology; Japan; Laser Therapy; Lentigo - etiology; Lentigo - surgery; Pigmentation Disorders - etiology; Prospective Studies; Sunlight - adverse effects
• ISSN: 0926-9959; 1468-3083
• DOI: 10.1111/j.1468-3083.2011.04385.x

Background  Quality‐switched (QS) lasers are well‐known effective treatment for removing solar lentigines. However, the high incidence of post‐inflammatory hyperpigmentation (PIH) raises concern in darker skin types. This is the first study comparing efficacies and incidences of PIH in Asian skin with different degrees of irradiation between two QS lasers. Method  In total, 355 solar lentigines in 193 cases, skin types III–V, were randomly divided into four groups. All cases received single laser treatment. Clinical results were evaluated after 4 weeks. Groups 1 and 3 were treated ‘aggressively’ with endpoints of very obvious immediate whitening (IW) of the lesion. Groups 2 and 4 were treated ‘mildly’ with endpoints of slight IW of the lesion. Groups 1 and 2 were irradiated with the QS ruby, and groups 3 and 4 with the QS frequency doubled Nd:YAG laser. Results  There were no statistically significant differences in degrees of clearance among the four groups. However, PIH incidences were very different: 33.33%, 7.47%, 23.18% and 8.47% in groups 1, 2, 3 and 4 respectively. The difference between aggressively and mildly irradiated groups (1 and 3 vs. 2 and 4) was statistically significant (P