To examine relationships between chemical composition, biopsy findings,and clinical outcome in laser-treated tattoos.
Observational nonblinded retrospective study.
University-based dermatology clinic and private practice.
Twenty patients who underwent biopsy of laser-treated tattoos.
Main Outcome Measures
Biopsy specimens were analyzed after laser treatment, and the depthsof changed particles were recorded. Ultrastructure of the changed particleswas examined by electron microscopy. Presence of inorganic chemicals was determinedby x-ray diffraction. Correlation between x-ray diffraction, microscopy, andclinical response was attempted.
Of the 20 tattoos, 7 lightened, 9 failed to change, and 4 darkened afterlaser treatment. There was a significant association between presence of titaniumdioxide and poor response to laser therapy. Microscopic studies showed variablechanges in the ink particles, but there was a trend toward residual deep greenpigment in the resistant tattoos. Also, round dark stippling was observedsuperficially in the darkened specimens.
Titanium is overrepresented in tattoos that respond poorly to lasertreatment. Further studies are necessary to show whether this metal is theprimary cause of this poor response.