title: Tattoo darkening and nonresponse after laser treatment: a possible role for titanium dioxide.
abstract: OBJECTIVE
  To examine relationships between chemical composition, biopsy findings, and clinical outcome in laser-treated tattoos.
  
  
  METHODS
  Observational nonblinded retrospective study.
  
  
  METHODS
  University-based dermatology clinic and private practice.
  
  
  METHODS
  Twenty patients who underwent biopsy of laser-treated tattoos.
  
  
  METHODS
  Biopsy specimens were analyzed after laser treatment, and the depths of changed particles were recorded. Ultrastructure of the changed particles was examined by electron microscopy. Presence of inorganic chemicals was determined by x-ray diffraction. Correlation between x-ray diffraction, microscopy, and clinical response was attempted.
  
  
  RESULTS
  Of the 20 tattoos, 7 lightened, 9 failed to change, and 4 darkened after laser treatment. There was a significant association between presence of titanium dioxide and poor response to laser therapy. Microscopic studies showed variable changes in the ink particles, but there was a trend toward residual deep green pigment in the resistant tattoos. Also, round dark stippling was observed superficially in the darkened specimens.
  
  
  CONCLUSIONS
  Titanium is overrepresented in tattoos that respond poorly to laser treatment. Further studies are necessary to show whether this metal is the primary cause of this poor response.
authors.affiliation: Department of Dermatology, Naval Medical Center, 34800 Bob Wilson Dr, Suite 5, San Diego, CA 92134-1005, USA. evross@nmcsd.med.navy.mil
authors.forename: E V
authors.initials: EV
authors.lastname: Ross
authors.forename: S
authors.initials: S
authors.lastname: Yashar
authors.forename: N
authors.initials: N
authors.lastname: Michaud
authors.forename: R
authors.initials: R
authors.lastname: Fitzpatrick
authors.forename: R
authors.initials: R
authors.lastname: Geronemus
authors.forename: W D
authors.initials: WD
authors.lastname: Tope
authors.forename: R R
authors.initials: RR
authors.lastname: Anderson
mesh_terms: D004396:Coloring Agents / Q000032:analysis / Q000528:radiation effects; D006801:Humans; D053685:Laser Therapy; D008854:Microscopy, Electron; D012189:Retrospective Studies; D013653:Tattooing; D014025:Titanium / Q000032:analysis / Q000528:radiation effects; D014961:X-Ray Diffraction
chemical_list: D004396:Coloring Agents; C009495:titanium dioxide; D014025:Titanium