title: Spectroscopic assessment of dermal melanin using blue vitiligo as an in vivo model.
abstract: BACKGROUND
  Spectroscopic methods have been used to analyze in vivo melanin in the past but the specific effect of melanin depth on autofluorescence and reflectance spectroscopy has not been determined. In patients with blue vitiligo, three distinctive clinicopathologic patterns are present: (1) normal skin with normal epidermal melanin pigmentation (2), skin of blue vitiligo with dermal melanin pigmentation, and (3) tissue of regular vitiligo with no melanin pigmentation. Blue vitiligo may thus serve as an in vivo model to assess dermal pigment using spectroscopic techniques.
  
  
  OBJECTIVE
  To evaluate the reflectance and autofluorescence spectra of a patient with blue vitiligo in order to assess the effect of melanin pigmentation and its localization on the optical properties of the skin.
  
  
  METHODS
  The blue-gray, normal and depigmented lesions of a patient with blue vitiligo were analyzed using reflectance and fluorescent spectroscopy. The condition was likely induced by a phototoxic reaction in a patient with pre-existing vitiligo. These data were then correlated to the histologic and electron microscopic findings present in the various types of lesions.
  
  
  RESULTS
  Reflectance spectroscopy detected little difference in spectral shape between skin sites affected by blue vitiligo vs. vitiligo. Autofluorescence spectroscopy detected an apparent difference between the two types of lesions, with the blue-gray lesions (blue vitiligo) showing lower fluorescence intensity and spectral maximum position red-shifted compared with regular vitiligo, whereas regular vitiligo showed more intense hemoglobin absorption than the blue vitiligo.
  
  
  CONCLUSIONS
  Dermal melanin present in blue vitiligo can be well characterized by autofluorescence spectroscopy, while little difference in reflectance spectral shape exists between vitiligo and blue vitiligo. Thus, autofluorescence spectroscopy may better identify deeper structures in skin tissue, such as melanin, than reflectance spectroscopy.
authors.affiliation: Division of Dermatology, University of British Columbia and Vancouver General Hospital, Vancouver, Canada.
authors.forename: Iltefat
authors.initials: I
authors.lastname: Hamzavi
authors.forename: Natalie
authors.initials: N
authors.lastname: Shiff
authors.forename: Magda
authors.initials: M
authors.lastname: Martinka
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Huang
authors.forename: David
authors.initials: D
authors.lastname: McLean
authors.forename: Haishan
authors.initials: H
authors.lastname: Zeng
authors.forename: Harvey
authors.initials: H
authors.lastname: Lui
mesh_terms: D006801:Humans; D008297:Male; D008543:Melanins / Q000378:metabolism*; D008875:Middle Aged; D013057:Spectrum Analysis / Q000379:methods*; D014467:Ultraviolet Therapy; D014820:Vitiligo / Q000378:metabolism* / Q000532:radiotherapy
chemical_list: D008543:Melanins