Histologic effects of ruby laser hair removal in Japanese patients

Background and Objective: Hair removal by lasers has recently become a popu lar method to remove unwanted hair. However, histologic changes in human sk in before and after exposure to lasers have not been thoroughly investigate d. The aim of this study was to clarify the differences that occur immediat ely after laser exposure and 1 month after laser exposure. Study Design/Materials and Methods: Eight adult Japanese volunteers were re cruited for this study. They were treated with a long pulsed ruby laser at 20 J/cm(2). A single 3-mm punch biopsy of the laser-treated sites was obtai ned immediately after laser irradiation and at the 1-month follow-up visit, and they were analyzed using hematoxylin and eosin, PAM, and immunohistolo gical staining. Results: Immediately after laser exposure, hair follicles were very damaged and had extensive eosinophilic degeneration. One month after laser therapy , one type of hair follicle showed cystlike formations with negative prolif erating cell nuclear antigen reactions (PCNA). Another type of hair follicl e showed follicular mitotic figures with cytoplasmic halos. Early anagen ha ir follicles were apparently not treated effectively by ruby laser. Conclusion: Ruby laser leads to extensive follicular damage, and hair folli cles considered to be at early anagen phase were not effectively treated. T his may be the reason several courses of laser therapy are required to obta in satisfactory results. Lasers Surg. Med. 25:451-455, 1999. (C) 1999 Wiley -Liss, Inc.