Table 1.

Features of colonic polyp subtypes

Polyp nameAlternative terminologyMorphology and significanceMolecular features
AdenomaAdenomatous polypNeoplastic polyp with malignant potentialBRAF mutation and CIMP rare (5, 92)
Serrated polypVarious (see below)General term for all colorectal polyps with glandular serration
Hyperplastic polyp, goblet typeType 1 hyperplastic polypSubtype of hyperplastic polyp with conspicuous goblet cells and showing the least morphologic deviation from normal; described as goblet-cell rich type. Found predominantly in the distal colonFrequent KRAS mutation (54%; ref. 89)
Hyperplastic polyp, microvesicular typeType 2 hyperplastic polypVariant of hyperplastic polyp in which columnar cells have mucin-filled vesicles within the apical cytoplasm and goblet cells are relatively inconspicuousFrequent BRAF mutation (76%) and CIMP (68%; ref. 89)
SSASessile serrated polyp. Serrated polyp with atypical proliferationAdvanced type of serrated polyp with abnormalities of architecture and proliferation but lacking the classic features of epithelial dysplasia (intraepithelial neoplasia)Frequent BRAF mutation (75-82%) and CIMP (92%; refs. 5, 89)
MPAdmixed polypRare serrated polyp that includes two separate components. One component is usually nondysplastic (usually SSA) whereas the second dysplastic component is either traditional adenoma or serrated adenoma; partly hyperplastic polyp and partly adenoma. Polyps with mixtures of adenoma and SA have also been described as mixed polypsFrequent BRAF mutation, especially when SSA forms part of the lesion (89%; ref. 5)
SA(a) Mixed hyperplastic adenomatous polyp. (b) Atypical hyperplastic polyp. (c) Traditional SARelatively rare neoplastic polyp having a serrated architecture reminiscent of hyperplastic polyp but with unequivocal traditional adenomatous dysplasia. Comprises <5% of serrated polypsMarked molecular heterogeneity. Overlapping molecular pathways. May have either KRAS or BRAF mutation or and features of the adenoma-carcinoma pathway
  • NOTE: Data are adapted from ref. 16.