Fluorescence Imaging of Cutaneous Malignant Melanomas and Naevi

Fluorescence images of skin lesions of 140 patients were recorded in vivo, including 53 melanomas and 42 naevi. All lesions (140) were validated by histology. Fluorescence was excited at λ_ex=365 nm and observed within the optical band pass 450 nm<λ_obs<500 nm using a cooled CCD camera. For discrimination of melanomas and naevi, recorded fluorescence intensities were averaged over the lesions (I _lesion) and over selected areas of healthy skin (I _skin). Normalised cumulative frequencies of naevi and melanomas differ slightly, when plotted versus the ratio I _skin/I _lesion, with the cumulative frequency of melanomas shifted towards higher ratios. However, because of strong overlap, diagnosis of melanomas and naevi is not improved significantly contrary to reports in the literature. More specifically, 26% of melanomas (43% of naevi) are falsely classified as naevi (melanomas) when using the ratio I _skin/I _lesion exclusively. Furthermore, spatial distribution of fluorescence intensities (450 nm<λ_obs<500 nm) does not allow discrimination between melanomas and naevi.