Efficacy and Safety of Long-Pulsed 755-nm Alexandrite Laser for Keratosis Pilaris: A Split-Body Randomized Clinical Trial

Keratosis pilaris (KP) is a disfiguring disease and is resistant to treatment. Several treatment methods are available, but the efficacy is limited. This prospective, rater-blinded, split-body comparative study investigated the efficacy and safety of long-pulsed 755-nm alexandrite laser in the treatment of KP.

Twenty-two patients with KP of bilateral arms were enrolled in this study. All participants were randomized and treated with a long-pulsed 755-nm alexandrite laser on the left or right arm in four sessions held 3 weeks apart. The unified moisturizing lotion was applied on both left and right arms once a day. Physicians’ assessment scores and patients’ self-assessment scores were recorded, and skin imaging changes in dermoscopy, high-frequency ultrasound, and skin biopsy were obtained at baseline and 4 weeks after the fourth treatment.

Of the 21 patients who completed the study, 15 were women and 6 were men. At 4 weeks after the fourth treatment, the laser side showed significantly lower total (2.0 versus 4.5), roughness (1.0 versus 2.0), and redness (1.0 versus 2.0) scores according to physicians’ assessment (all P < 0.05). Furthermore, the laser side showed significantly lower total (2.0 versus 4.0), roughness (1.0 versus 2.0), and redness scores (1.0 versus 2.0) according to the patients’ self-assessment (all P < 0.05). The proportions of patients who achieved dermoscopically and ultrasonographically showed excellent improvements in follicular plugs (57.1% versus 14.3%), perifollicular erythema (52.4% versus 9.5%), perifollicular hyperpigmentation (47.6% versus 14.3%), and the number of epidermal bulges (57.1% versus 19.1%) in the laser side was significantly higher than those who achieved such improvements in the control side (all P < 0.05). Histopathology showed that the follicular plugs and inflammatory cell infiltration were improved at the final visit. Three patients exhibited reversible postinflammatory hyperpigmentation.

Long-pulsed 755-nm alexandrite laser treatment is effective and safe in treating both skin roughness and redness in KP.