Hyperplastic polyp or sessile serrated lesion? The contribution of serial sections to reclassification

Abstract

Background The histological discrimination of hyperplastic polyps from sessile serrated lesions can be difficult. Sessile serrated lesions and hyperplastic polyps are types of serrated polyps which confer different malignancy risks, and surveillance intervals, and are sometimes difficult to discriminate. Our aim was to reclassify previously diagnosed hyperplastic polyps as sessile serrated lesions or confirmed hyperplastic polyps, using additional serial sections. Methods Clinicopathological data for all colorectal hyperplastic polyps diagnosed in 2016 and 2017 was collected. The slides were reviewed and classified as hyperplastic polyps, sessile serrated lesion, or other, using current World Health Organization criteria. Eight additional serial sections were performed for the confirmed hyperplastic polyp group and reviewed. Results Of an initial 147 hyperplastic polyps from 93 patients, 9 (6.1%) were classified as sessile serrated lesions, 103 as hyperplastic polyps, and 35 as other. Of the 103 confirmed hyperplastic polyps, 7 (6.8%) were proximal, and 8 (7.8%) had a largest fragment size of ≥5 mm and < 10 mm. After 8 additional serial sections, 11 (10.7%) were reclassified as sessile serrated lesions. They were all less than 5 mm and represented 14.3% of proximal polyps and 10.4% of distal polyps. An average of 3.6 serial sections were required for a change in diagnosis. Conclusion Histopathological distinction between hyperplastic polyps and sessile serrated lesions remains a challenge. This study has uncovered a potential role for the use of additional serial sections in the morphological reappraisal of small hyperplastic polyps, especially when proximally located.

Disparate age and sex distribution of sessile serrated lesions and conventional adenomas in an outpatient colonoscopy population–implications for colorectal cancer screening?

“…Approximately two-thirds of CRCs are derived from conventional adenomas, henceforth referred to as adenomas. However, the serrated neoplasia pathway is another important contributor to CRC, accounting for approximately Vidit Lall and Ali Galalah Mostafa Ismail are equal first authors one-third of sporadic CRCs [4][5][6]. The World Health Organisation (WHO) currently identifies three different types of serrated polyps: hyperplastic polyps (HP), sessile serrated lesions (SSL−previously known as sessile serrated adenomas/ polyps), and traditional serrated adenomas (TSA) [7].…”

“…The World Health Organisation (WHO) currently identifies three different types of serrated polyps: hyperplastic polyps (HP), sessile serrated lesions (SSL−previously known as sessile serrated adenomas/ polyps), and traditional serrated adenomas (TSA) [7]. SSLs are of contemporary interest, as their detection may be challenging and awareness regarding their prevalence and malignant potential is increasing [4,5]. Furthermore, SSLs seem to be associated with a disproportionately high number of interval CRCs compared to their reported prevalence [8].…”

“…Histopathologically, the WHO recently defined SSLs as "serrated polyps with ≥ 1 unambiguous distorted crypt", which is more sensitive than the previous diagnostic criteria from 2010 requiring "pathological features in two or three adjacent crypts" [7,9]. This has led to a considerable proportion of previously diagnosed HPs being reclassified as SSLs [5,10]. Molecularly, the serrated pathway is known to exhibit high amounts of cytosine-phosphate-guanine (CpG) island methylation and can express microsatellite instability.…”

Clinicopathological and molecular analyses of hyperplastic lesions including microvesicular variant and goblet cell rich variant hyperplastic polyps and hyperplastic nodules—Hyperplastic nodule is an independent histological entity

“…According to these findings, HPs may not be trivial lesions in terms of molecular pathology. However, pathologists may not recognize GCHPs as having a neoplastic nature because they exhibit little or no histological atypia 1–3,20 . Among Japanese pathologists, HNs, which resemble GCHPs histologically, have been used in routine histological diagnosis.…”

“…However, pathologists may not recognize GCHPs as having a neoplastic nature because they exhibit little or no histological atypia. 1 , 2 , 3 , 20 Among Japanese pathologists, HNs, which resemble GCHPs histologically, have been used in routine histological diagnosis. If HNs do not have any specific gene mutations, then they may be non‐neoplastic lesions that should be distinguished from GCHPs, which may be preneoplastic lesions.…”