Evaluation of the efficacy of laser-based endomicroscopy as a complement to white-light colonoscopy and chromoendoscopy for early detection of colon dysplasia in patients with PSC-IBD. White-light colonoscopy is a routinely used procedure in colorectal cancer surveillance programs. However, it does not permit detection of early dysplastic lesions. Chromoendoscopy by applying a dye (indigo-carmine) through the colonoscope helps to identify flat lesions but is not suitable for accurate endoscopic diagnosis of dysplasia and intraepithelial neoplasia Under this aim we will perform a clinical study evaluating a newly developed technique allowing for in vivo confocal microscopy assessment of the colon mucosa using laser-based endomicroscopy together with intravenous administration of fluorescein (FITC).