[Pathohistology of polyps of the gastrointestinal tract]

Polyps of the gastrointestinal tract encompass a variety of epithelial and non-epithelial tumour-like conditions. The most common polyps are epithelial lesions. In the upper gastrointestinal tract, reactive inflammatory changes and hyperplastic polyps dominate, whereas true neoplastic polyps, like adenomas, are much more common in the colorectum. In addition to neoplasias such as adenomas, non-neoplastic polyps such as hyperplastic polyps of the stomach may also be associated with an increased risk of malignancy. The risk of malignancy is determined by the histological subtype of polyp, as well as the size, presence and degree of dysplasia. The term "dysplasia" has been reintroduced for adenomas in the current 2019 World Health Organization (WHO) classification and replaces "intraepithelial neoplasia". A further change is the term "sessile serrated lesion" with and without dysplasia, which was formerly known as sessile serrated adenoma.