Traditional serrated adenomas (TSAs) admixed with other serrated (so-called precursor) polyps and conventional adenomas: a frequent occurrence

Abstract

More than 50% of TSAs are associated with a precursor lesion or adjacent TA/TVA. Their recognition is important as this may have surveillance and management ramifications.

Serrated lesions in colorectal cancer screening: detection, resection, pathology and surveillance

“…The TSA is a rare lesion located primarily in the left colon and rectum 14 15. TSA is the only member of the serrated class that is uniformly dysplastic.…”

Traditional serrated adenoma: an update

“…In addition, some TSAs, in particular, small polyps, do not show ECFs [6,8]. Several recent publications have reemphasized the striking similarity between the TSA and the normal small bowel epithelium as a critical component of the diagnosis [6,[20][21][22]. In particular, the characteristic cytologic appearance of the TSA and the presence of a distinctive form of serration are very useful clues to making the diagnosis.…”

“…In our opinion, this finding has now been so well documented by numerous groups that it should no longer be an issue of debate. In fact, 30% to 50% of TSAs appears to arise in 1 of these precursors [6,8,9,22]. The relative proportions arising in MVHPs versus SSAs are somewhat variable and likely reflect differences in diagnostic criteria.…”

Targeting the serrated pathway of colorectal cancer with mutation in BRAF

“…Finally, TSAs appear usually in the distal colon and are rare (2-5% of all colorectal polyps) with distorted tubulovillous (filiform) architecture, resembling in part the 'traditional' adenomatous polyps, and show the presence of ectopic crypt foci [20,21]. In addition, the admixed occurrence of TSA adjacent to HP, SSA, or conventional adenomas is frequent (up to 52% of TSAs), so that morphological classification is sometimes difficult to score and contributes to different frequency values for serrated polyps described in the literature [22]. Table 2 summarizes the main features that distinguish the different serrated polyp types (for histo-pathological details see the specialized reviews [7,14,16,20,23]).…”

“…Such tumors are mostly derived from TSAs with more adenomatous features and occur in the distal colon with a poor prognosis [22]. These characteristics can be replicated upon expression of mutant KRAS in the intestinal epithelium of transgenic mice [41].…”