Adenomas and adenoma-like DALMs in chronic ulcerative colitis: a clinical, pathological, and molecular review

Dysplasia in chronic ulcerative colitis (CUC) is categorized as either flat or associated with a raised lesion or mass (dysplasia-associated lesion or mass [DALM]). One specific subtype of DALM consists of an isolated discrete "adenoma-like" polypoid dysplastic lesion that is difficult to distinguish from a sporadic adenoma that occurs coincidentally in patients with CUC. Sporadic adenomas are, by definition, also polypoid dysplastic lesions, but their development is unrelated to the underlying colitis. The clinical distinction between CUC-associated polypoid dysplastic lesions and sporadic adenomas is important because the former is an indication for colectomy whereas the latter is usually treated by simple polypectomy. This review focuses on the clinical, pathological, and molecular aspects of polypoid dysplastic lesions and sporadic adenomas in CUC. There are a variety of clinical and pathological features that can be used to distinguish these lesions, but none of these features are entirely specific for either type of neoplasm. Furthermore, there is recent evidence to suggest that the molecular pathogenesis of CUC-associated polypoid dysplasia is different, in terms of the order and timing of genetic events, in comparison to sporadic adenomas and, thus, this information may be used to distinguish these lesions in the near future. Few studies have evaluated the natural history of CUC-related polypoid dysplastic lesions and sporadic adenomas. However, recent reports indicate that the majority of these lesions will follow a relatively benign course with a low risk of progression to flat dysplasia or adenocarcinoma. This review also summarizes the current provisional treatment recommendations for CUC patients with an adenoma-like polypoid dysplastic lesion.