title: Influence of the frequency of laser toning for melasma on occurrence of leukoderma and its early detection by ultraviolet imaging.
abstract: OBJECTIVE
  Laser "toning" with a Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser has recently been described to be effective for the treatment of melasma. Leukoderma is a refractory complication of laser toning for melasma, but it can be detected early with ultraviolet (UV) imaging. We assessed the relationship between leukoderma and the frequency or total number of laser toning sessions, as well as the effectiveness of UV imaging for detecting leukoderma.
  
  
  METHODS
  The subjects included 147 patients who received at least five laser toning sessions. Subjects were classified into three groups according to the frequency of treatment (weekly for Group A1, fortnightly for Group A2, and monthly for Group B), and the incidence of leukoderma was compared among the three groups. In patients who developed leukoderma, the interval between clinical diagnosis and leukoderma detection on UV images (obtained with a Visia Evolution during every laser toning session) was determined to evaluate the effectiveness of UV imaging for the early detection of leukoderma.
  
  
  RESULTS
  The overall incidence of leukoderma was 2% (3/147 patients): 3.8% (1/26 patients) in Group A1, 4% (2/49 patients) in Group A2, and 0% (0/72 patients) in Group B. There were no significant differences in the incidence of leukoderma relative to the frequency of laser toning. In two of the three patients who developed leukoderma, it was diagnosed clinically at the 20th and 21st laser toning session, whereas it was diagnosed by UV imaging at the 12th and 13th session. In the remaining 1 patient, leukoderma was detected clinically and by UV imaging at the 7th session.
  
  
  CONCLUSIONS
  There was no significant difference in the incidence of leukoderma related to the frequency of laser toning. This study showed that there are two types of leukoderma associated with laser toning. UV imaging was effective for the early detection of type 1 leukoderma, which seems to be related to the cumulative laser energy delivered, but not for detecting type 2 leukoderma, which may be due to direct phototoxicity.
authors: Department of plastic and Reconstructive Surgery,, Yokohama City University Medical Center, Yokohama, Japan.
authors: Jun
authors: J
authors: Sugawara
authors: Seiko
authors: S
authors: Kou
authors: Sousei
authors: S
authors: Kou
authors: Kazunori
authors: K
authors: Yasumura
authors: Toshihiko
authors: T
authors: Satake
authors: Jiro
authors: J
authors: Maegawa
mesh_terms: D000328:Adult; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D017496:Hypopigmentation / Q000000981:diagnostic imaging* / Q000453:epidemiology* / Q000473:pathology; D015994:Incidence; D053685:Laser Therapy / Q000009:adverse effects* / Q000379:methods*; D053844:Lasers, Solid-State / Q000009:adverse effects*; D008548:Melanosis / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D008875:Middle Aged; D012189:Retrospective Studies; D014463:Ultrasonography
keywords: Q-switched 1,064nm Nd:YAG laser; UV imaging; laser toning; leucoderma; melasma