It is well recognized that carcinoma of the colon is the major complication in patients with long-standing inflammatory bowel disease (IBD). The first report of a rectal carcinoma arising in long-standing ulcerative colitis (UQ was from Crohn and Rosenberg in 19251. After this first report, numerous other reports established the clinical and morphological features observed in UC undergoing malignant change. In 1949 Warren and Sommers2 analysed the pathogenesis of UC and sustained the concept of a 'precancerous epithelial hyperplasia' stage. Morson and Pang3 in 1967 proposed the use of rectal biopsy in the surveillance and diagnosis of cancer in UC patients. Despite the general agreement that extensive and long-standing disease predisposes to the development of colorectal neoplasia, the recognition and grading of the first steps of the neoplastic process have been a controversial issue. The concept of dysplasia as a premalignant lesion was then developed in the context of IBD and remains the gold standard to identify high-risk patients.
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