LASER-INDUCED FLUORESCENCE MICROSCOPY OF NORMAL COLON AND DYSPLASIA IN COLONIC ADENOMAS - IMPLICATIONS FOR SPECTROSCOPIC DIAGNOSIS

Objectives: To determine what structures fluoresce and to what extent in normal colon and colonic adenomas to fully exploit laser-induced fl uorescence spectroscopy as a tool for the diagnosis of dysplasia at en doscopy, Methods: Unstained frozen sections of normal colon and coloni c adenomas were studied by fluorescence microscopy under 351-364-nm ar gon ion laser excitation, Tissue fluorescence was observed and compare d to morphology in serial sections stained with hematoxylin and eosin (H&F), Movat pentachrome, mucicarmine, and oil red O, Results: In norm al colon, fluorescence correlated morphologically with connective tiss ue fibers (principally collagen) in all layers of the bowel wall and w ith cytoplasmic granules within eosinophils present between the crypts in the lamina propria of the mucosa, Fluorescence of absorptive cells in normal crypts was very faint, and Goblet cells did not fluoresce, However, marked fluorescence was observed in the cytoplasm of dysplast ic epithelial cells in the crypts of colonic adenomas, Fewer fluoresce nt connective tissue fibers were present in the lamina propria of colo nic adenomas resulting in decreased fluorescence intensity as compared to that of normal colon, Fluorescent eosinophil granules were present in larger numbers in adenomas as compared with normal colon, Conclusi on: Laser-induced fluorescence in normal colon and colonic adenomas co rrelates with morphology, Previous reported differences in laser-induc ed fluorescence emission spectra of normal colon and colonic adenomas obtained in vitro and in vivo may be due to differences in the cytopla smic fluorescence between the dysplastic epithelium in colonic adenoma s and normal colonic epithelium. Laser-induced fluorescence spectrosco py may be useful in studying other forms of epithelial dysplasia such as that which occurs in ulcerative colitis.