Endoscopic examination of the fluorescence pattern of dysplasia after sensitization with 5-aminolevulinic acid in patients with chronic ulcerative colitis

Abstract

In surveillance colonoscopy (SC) for patients with chronic ulcerative colitis (UC) , many endoscopic procedures have been performed, but reliable endoscopic detection methods still remain uncertain. Recently, photodynamic diagnosis (PDD) has been utilized clinically, especially in neurosurgical and urological procedures, to detect the extent of neoplasm. 5-Aminolevulinic acid (5-ALA) is converted intracellularly into the sensitizer protoporphyrin IX (PpIX) , which accumulates selectively in neoplastic tissue, allowing detection. As there are few reports regarding the use of 5-ALA for UC surveillance, its effectiveness and the 5-ALA-induced fluorescence pattern are still unclear. We previously reported the PpIX expression in dysplastic lesions, which was induced in a mouse model of colitis-associated cancer or dysplasia (CCD) . The aim of this study was to evaluate the fluorescence pattern after sensitization with 5-aminolevulinic acid (5-ALA) by using autofluorescence endoscopy (AFE) . Strong PpIX fluorescence signal was observed in both high- and low-grade dysplasia, especially at the margin of the low-grade dysplasia. AFE after 5-ALA sensitization offers the possibility of detecting CCD lesions by characteristic shape and color enhancement. Although the number of patients enrolled in this study was limited, our experience indicates that AFE is a promising method for detecting CCD lesions during UC surveillance.