title: Cutaneous melanin exhibiting fluorescence emission under near-infrared light excitation.
abstract: Under ultraviolet and visible light excitation, melanin is essentially a nonfluorescent substance. This work reports our study on near-infrared (NIR) fluorescence properties of melanins, and explores potential applications of NIR fluorescence techniques for evaluating skin disorders involving melanin. The NIR fluorescence spectrum is obtained using a fiber optic NIR spectrometer under 785-nm laser excitation. In vitro measurements are performed on synthetic dihydroxyphenylalanine (DOPA) melanin, melanin extracted from Sepia ink sacs, human hair, animal fur, and bird feathers. Paired spectral comparisons of white and black skin appendages show that melanization of hair, fur, or feathers more than doubles the NIR fluorescence. In vivo NIR autofluorescence of normal dorsal and volar forearm skin of 52 volunteers is measured. Dorsal forearm skin, which is darker than volar skin, exhibits significantly greater NIR fluorescence. Patients with vitiligo (n=4), compound nevus (n=3), nevus of Ota (n=1), superficial spreading melanoma (n=3), and postinflammatory hyperpigmentation (n=1) are also evaluated. NIR fluorescence is greater within the lesion than the surrounding normal skin for all these conditions except vitiligo, where the converse was true. The observed melanin NIR fluorescence provides a new approach to in vitro and in vivo melanin detection and quantification that may be particularly useful for evaluating pigmented skin lesions.
authors.affiliation: British Columbia Cancer Research Centre, Cancer Imaging Department, Vancouver, Canada.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Huang
authors.forename: Haishan
authors.initials: H
authors.lastname: Zeng
authors.forename: Iltefat
authors.initials: I
authors.lastname: Hamzavi
authors.forename: Abdulmajeed
authors.initials: A
authors.lastname: Alajlan
authors.forename: Eileen
authors.initials: E
authors.lastname: Tan
authors.forename: David I
authors.initials: DI
authors.lastname: McLean
authors.forename: Harvey
authors.initials: H
authors.lastname: Lui
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D002415:Cats; D005240:Feasibility Studies; D006801:Humans; D008163:Luminescent Measurements / Q000379:methods*; D008543:Melanins / Q000032:analysis*; D010859:Pigmentation Disorders / Q000175:diagnosis* / Q000378:metabolism*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D049833:Sepia; D012867:Skin / Q000378:metabolism*; D013055:Spectrophotometry, Infrared / Q000379:methods*
chemical_list: D015415:Biomarkers; D008543:Melanins