Fluorescence detection to diagnose melanoma : Analternative objective method for dermatohistology

Abstract

Dermatohistological assessment is the gold standard in the diagnosis of melanoma. As asubjective method, this depends, among other things, on the expertise of the examiner. Anew objective method of investigation-dermatohistofluoroscopy-aims to improve the diagnostic reliability of melanoma diagnosis. The ultra-weak spectrally resolved fluorescence of melanin of pigment-bearing skin cells is areliable indicator of the malignancy of the tissue to be diagnosed. Using aspecial laser spectroscopic method, this fluorescence can be measured on histological specimen (and also on tissue in vivo and on excidate). Melanocytes from normally pigmented skin, nevomelanocytes from benign and dysplastic nevi, and melanoma cells each show characteristic, different fluorescence spectra. If these cell types are shown spatially resolved in different colors on the preparation to be diagnosed, they give the histologist an objective basis for the diagnosis, even in difficult cases, e.g., the so-called stumbling blocks of melanoma diagnosis such as Spitzoid tumors. Currently, the method can only be used for Fitzpatrick skin types1 and2. In addition, aseparate second measurement signal at 400 nm can be used to identify tumor breakthrough through the basement membrane. This signal is collagen bound, so it also appears in amelanotic melanomas, to which the method is otherwise inherently inapplicable.