Dysplasia in inflammatory bowel disease.

Ulcerative colitis and Crohn's diseases are relapsing longstanding inflammatory bowel diseases, associated with an increased risk of developing colorectal cancer. Continuous surveillance is necessary to detect the preneoplastic lesions in an early stage. New endoscopic techniques have improved the diagnostic accuracy and have resulted in a new and more simplified classification system of the dysplastic lesions in the bowel. Histopathologically these lesions are very heterogenous, consisting of adenomatous, villous and the more recently discovered serrated dysplasia. Its diagnosis may be hampered by the inflamed mucosa, resulting in a high interobserver variability in the categories of indefinite for dysplasia and low-grade dysplasia. Therefore the ECCO guidelines recommend to confirm the diagnosis of dysplasia by a pathologist with expertise in gastrointestinal pathology. In this article we give an overview of colitis-associated dysplasia from the point of view of the endoscopist and the pathologist.