DIFFERENCES IN LASER-INDUCED AUTOFLUORESCENCE BETWEEN ADENOMATOUS ANDHYPERPLASTIC POLYPS AND NORMAL COLONIC MUCOSA BY CONFOCAL MICROSCOPY

Laser-induced autofluorescence has been used to discriminate normal fr om adenomatous colonic mucosa. However, few studies to date have studi ed the origin of colonic autofluorescence. Using confocal microscopy ( excitation wavelength 488 nm), we have shown that autofluorescence at this wavelength is present predominantly in the lamina propria of norm al mucosa but in the epithelium in adenomatous and hyperplastic polyps . The intensity ratio of epithelial cell to lamina propria fluorescenc e was significantly lower (P < 0.0001) in normal mucosa (0.52 +/- 0.01 ) compared with either adenomatous (1.6 +/- 0.2) or hyperplastic polyp s (1.7 +/- 0.15). However, the ratios were not significantly different between hyperplastic and adenomatous polyps. Thus, confocal microscop y enables the detection of the sites of autofluorescence within coloni c mucosa and the quantitation of differences in fluorescence between d ifferent tissue types.