Serrated colorectal polyps

The advent of national colorectal cancer screening in the UK has produced a rich supply of unusual polyps for histopathologists to classify. In amongst the thousands of tubulovillous adenomas there are some interesting serrated polyps which may denote an increased risk of colorectal cancer. In this month’s Journal of Clinical Pathology Adrian Bateman and Neil Shepherd provide a very useful summary of these lesions with some excellent photomicrographs. They give a recommended terminology for serrated lesions of hyperplastic polyp, sessile serrated lesion, sessile serrated lesion with dysplasia, traditional serrated adenoma and mixed polyp (though they comment that most ‘mixed’ polyps are in fact sessile serrated lesions with or without dysplasia). The key differentiation is between hyperplastic polyps and serrated sessile lesions since the latter carry an increased risk of colorectal cancer, in contrast to the former.