Vascularity and Thickness Changes in Immature Hypertrophic Scars Treated With a Pulsed Dye Laser

Growth of capillaries is an essential process after a dermal injury. An immature scar with robust growth of capillaries tends to be hypertrophic. Pulsed dye laser (PDL) causes damage to microvascular structures and is increasingly used for early erythematous scars to limit scar growth. To have a better understanding of the impact of PDL on scar vascularity and to optimize the clinical use of PDL for managing hypertrophic scars, this study aimed to explore changes in scar erythema, blood perfusion, and thickness of immature hypertrophic scars in Asian patients who received PDL treatments at an early stage.This was a 3-month, assessor-blinded, clinical study. There were two groups of patients, the PDL group and the control group, who had hypertrophic scars less than 1-year post-injury. Patients in the PDL group received three PDL sessions at 4-week intervals. A total of three assessments were performed, at baseline, 1 and 3 months, consisting of the Patient and Observer Scar Assessment Scale (POSAS) and objective measurements of scar erythema, blood perfusion, and scar thickness.A total of 45 patients were enrolled, 22 in the PDL group and 23 in the control group. After the 3-month treatment, parameters of scar vascularity (P = 0.003), pigmentation (P = 0.026), color (P < 0.001), thickness (P < 0.05), and overall scores (P < 0.01) on the POSAS significantly decreased in the PDL group. Moreover, objective measurements of scar erythema and blood perfusion showed significant improvements in the PDL group (P = 0.009 and P = 0.022, respectively) but not in the control group (P = 0.296 and P = 0.115, respectively). A stable scar thickness was maintained in the PDL group from baseline to 3 months (0.21 cm vs. 0.22 cm, P > 0.05), whereas scar thickness significantly increased in the control group (0.22 cm vs. 0.32 cm, P < 0.01).Use of PDL at an early stage controls vascularity of immature hypertrophic scar by improving its poor blood perfusion that further limits scar thickness growth and promotes scar maturation. Lasers Surg. Med. 00:00-00, 2020. © 2020 Wiley Periodicals LLC.