• colorectal carcinoma;
  • epithelial–mesenchymal transition;
  • prognosis;
  • tumour budding

The term tumour budding denotes that at the invasion front of colorectal adenocarcinomas tumour cells, singly or in small aggregates, become detached from the neoplastic glands. This morphological feature is increasingly being recognized as a strong and robust adverse prognostic factor. Biologically, tumour budding is closely related to the epithelial–mesenchymal transition. In this review the morphological features of tumour budding are discussed, as observed by the surgical pathologist reporting colorectal carcinoma resection specimens. The morphological features are put into context with the rapidly expanding knowledge of the epithelial–mesenchymal transition in general, and the molecular pathology of colorectal carcinoma in particular. Finally, a systematic analysis of the relevant published clinicopathological studies emphasizes the potential of tumour budding as a prognostic factor for routine surgical pathology.