. 2022 Mar 3;80(7):1019–1025. doi: 10.1111/his.14618

Table 1.

Definitions of colorectal adenoma, as derived from the World Health Organisation classification of tumours (various editions)

WHO classification	Definition
1^st edition ¹⁷	A benign pedunculated or sessile neoplasm of glandular epithelium in which there is atypia of varying degrees.
2^nd edition ²⁰	A circumscribed benign neoplasm composed of tubular and/or villous structures lined by dysplastic epithelium. Dysplastic epithelium differs from the normal in including a higher proportion of immature cells containing large, hyperbasophilic and stratified nuclei.
3^rd edition ²¹	These precursor lesions are defined by the presence of intraepithelial neoplasia, histologically classified by hypercellularity with enlarged hyperchromatic nuclei, varying degrees of nuclear stratification and loss of polarity.
4^th edition ¹⁰	Adenomas are defined by the presence of dysplastic epithelium
5^th edition ¹²	Benign, premalignant neoplasms composed of dysplastic epithelium