Can Autofluorescence Demarcate Basal Cell Carcinoma from Normal Skin? A Comparison with Protoporphyrin IX Fluorescence
Fluorescence detection may help to demarcate skin cancer from normal skin, thus to reduce the potential of incomplete treatment resulting from unawareness of tumour extension in surrounding skin. In this study we evaluated the difference between autofluorescence of basal cell carcinomas (n = 21) and the normalappearing skin surrounding them. Referring to the difference found, a point-by-point measurement was taken from the tumour lesions outwards to the surrounding skin to locate the differentiation point of autofluorescence on the skin. Protoporphyrin IX fluorescence was measured from the same spots using the same procedure, after the tumours and the surrounding skin had been treated with topical 5-aminolevulinic acid methyl ester cream. The point-by-point measurement enabled us to locate the vanishing point of the protoporphyrin IX peak, which was compared with the differentiation point of autofluorescence to assess the utility of autofluorescence in tumour demarcation. Illuminated by 370nm light, both the tumour and surrounding skin emitted a fluorescence with peak intensity at 455 - 3nm. The peak intensity was 53% (18-84%) (median, range) lower in the tumours than in normal skin (p < 0.001). In 78 % of the measurements, the differentiation point of the autofluorescence was within 3mm of the vanishing point of the protoporphyrin IX peak. Autofluorescence may be used in BCC demarcation.