Purpose of review: To examine and clarify the nomenclature and histologic lesions identified as serrated mucosal lesions of the colorectum, including serrated adenomas, sessile serrated polyps (also known as sessile serrated adenomas) and hyperplastic polyps. This is timely given the significant confusion in ascribing a microscopic diagnosis and clinical utility of such a diagnosis.
Recent findings: The emergence of sessile serrated polyps (or adenomas) as distinct histomorphologic lesions from serrated adenomas, as well as the appreciation of the possibility of different modes of dysplasia exhibited in serrated lesions.
Summary: Clarification of the microscopic features, nomenclature and biology of serrated lesions are important for accurate histologic diagnosis, and in clinical terms for useful outcomes assessment, recommendations for follow-up and risk stratification.