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

Characteristics of Clinically Significant Hyperplastic Polyps: Distinctions Between Microvesicular and Goblet Cell-Rich Types

BACKGROUND

Clinically significant serrated polyps (CSSPs) are defined as sessile serrated lesions (SSLs), SSLs with dysplasia, traditional serrated adenomas (TSAs), hyperplastic polyps (HPs) ≥ 10 mm, and HPs ≥ 6 mm in the proximal colon. HPs are further classified as microvesicular HPs (MVHPs) and goblet cell-rich HPs (GCHPs). Among CSSPs, HPs were categorized into clinically significant MVHPs (CS-MVHPs) and clinically significant GCHPs (CS-GCHPs). This study compares the characteristics of CS-MVHPs, CS-GCHPs, and SSLs.

METHODS

This study included patients who underwent colonoscopy at the Toyoshima Endoscopy Clinic between March 2021 and April 2024. Lesions diagnosed as adenomas or CSSPs were removed. Age, sex, number of polyps, detection rate, and polyp size were compared among CS-MVHPs, CS-GCHPs, and SSLs.

RESULTS

In total, 14 065 patients were enrolled. The detection rates for CS-MVHPs, CS-GCHPs, and SSLs were 5.24%, 1.22%, and 6.36%, respectively. Patients with CS-MVHPs or SSLs were significantly younger and more often female than those with CS-GCHPs. The mean sizes of CS-MVHPs and SSLs were significantly larger than that of CS-GCHPs. The detection rate of CS-GCHPs increased with age, whereas the detection rates of CS-MVHPs and SSLs did not show a similar trend.

CONCLUSIONS

Compared with CS-GCHPs, CS-MVHPs were larger, more frequent, and more likely to be found in younger patients and females. The characteristics of CS-MVHPs are similar to those of SSLs, supporting the hypothesis that CS-MVHPs are precursors of SSLs.

Endoscopic characteristics to differentiate SSLs and microvesicular hyperplastic polyps from goblet cell-rich hyperplastic polyps

Background and study aims Among colorectal serrated polyps (SPs), sessile serrated lesions (SSLs) and hyperplastic polyps (HPs) have a similar endoscopic appearance. However, the endoscopic distinctions between those two categories, microvesicular HPs (MVHPs) and goblet cell-rich HPs (GCHPs), are not well understood. Therefore, we compared the endoscopic features of SSLs, MVHPs, and GCHPs. Methods This retrospective, cross-sectional study was conducted at the Toyoshima Endoscopy Clinic. We examined polyp size, location, Paris classification type, mucus cap, indistinct border, expanded crypt opening, varicose microvascular vessels, and JNET classification type. Multivariable analysis of each endoscopic finding using a binomial logistic regression model determined the factors that predicted SP histology. Results A total of 670 SPs were enrolled in this study, comprising 159 SSLs, 361 MVHPs, and 150 GCHPs. On comparing the SSL + MVHP group and the GCHP group, a mucus cap (partial regression coefficient 1.705), expanded crypt opening (1.828), and varicose microvascular vessels (1.270) were more often observed in the SSL + MVHP group compared with the GCHP group. In the comparison between MVHPs and GCHPs, a mucus cap (1.564), expanded crypt opening (1.802), and varicose microvascular vessels (1.288) were more often found in MVHPs in contrast to GCHPs. When comparing SSLs and MVHPs, SSLs were more likely to be in the proximal colon (0.662) and were larger (0.198) than the MVHPs. No significant differences were observed in other endoscopic findings. Conclusions SSLs and MVHPs have endoscopic appearances that differ from those of GCHPs. Considering MVHPs and GCHPs as distinct entities may aid in endoscopic diagnosis of SPs.

Morphological and molecular characterization of colorectal sessile serrated lesions with dysplasia

In sessile serrated lesions (SSLs) with adenomatous dysplasia, the dysplastic component and the serrated component without dysplasia should be considered as part of the same lesion, classified as SSL with dysplasia. However, some of these lesions may actually represent collisions between a serrated polyp and a conventional adenoma. Further supporting the "collision theory", conventional adenomatous dysplasia may be found in association with hyperplastic polyps (HPs). In order to determine the molecular and biological landscape of conventional type dysplasia in serrated lesions, we collected 17 cases of colorectal serrated lesions with adenomatous dysplasia, classifying them as SSL with dysplasia (n = 10) or as mixed lesions comprising a HP component and a conventional adenomatous component (n = 7). We characterized the dysplastic and the non-dysplastic component of each lesion, after microdissection, through the targeted mutational analysis of 11 commonly altered genes in colorectal cancer (AKT1, APC, BRAF, CTNNB1, KIT, KRAS, NRAS, PDGFRA, PIK3CA, PTEN and TP53). We also characterized MMR and p53 status by immunohistochemistry. Overall, 14/17 (82.4 %) cases harbored a mutation in at least one of the two components. The most altered genes were BRAF in 10/17 (58.8 %) cases, APC in 2/17 (11.8 %) and TP53 in 4/17 (23.5 %). Among the SSL with dysplasia, the mutational profile was concordant between the two components in 7/10 (70 %) cases, while among the mixed lesions, the mutational profile was concordant in 1/7 (14.3 %). In all but two cases of SSL with dysplasia, MMR status was concordant between the two components of the serrated lesions. Our findings suggest that adenomatous dysplasia may develop in SSL as part of the serrated lesion, even if some SSL with dysplasia may actually be collision lesions. On the other hand, the polyps that are morphologically classifiable as mixed lesions composed of a HP and a conventional adenomatous component are more likely to be collision lesions.