Large hyperplastic polyps of the colon

Inflammatory response in serrated precursor lesions of the colon classified according to WHO entities, clinical parameters and phenotype-genotype correlation

Studies on traditional serrated adenoma (TSA) and sessile serrated adenoma with dysplasia (SSA‐D) are rare due to the low frequency of these lesions, which are well defined by the latest WHO classification. However, introducing new morphological criteria such as intra‐epithelial lymphocytes (IELs) might facilitate colorectal polyp diagnoses. Additionally, the phenotype–genotype correlation needs to be updated as the terminology has repeatedly changed. This study analysed 516 polyps, consisting of 118 classical adenomas (CAD), 116 hyperplastic polyps (HPP), 179 SSAs, 41 SSA‐Ds, and 62 TSAs. The lesions were analysed in relation to the patients’ clinical parameters including gender, age, localisation, and size. The inflammatory background of the polyps was quantified and BRAF and KRAS mutations as well as MLH1 and CDKN2A promoter methylation were assessed. In multivariate analyses, an increase in IELs was an independent and robust new criterion for the diagnosis of SSA‐D (p < 0.001). Superficial erosions and acute neutrophil granulocytes led to reactive changes potentially resembling dysplasia. KRAS and BRAF mutations were associated with CAD/TSA and HPP/SSA, respectively. However, almost half of TSAs had a BRAF mutation and were KRAS wild type. CDKN2A seems to precede MLH1 hyper‐methylation within the serrated carcinogenesis model. The genotyping of WHO‐based entities – and especially SSA – has sharpened in comparison to previously published data. TSAs can be sub‐grouped according to their mutation status. Of note, the higher number of IELs in SSA‐D reflects their close relationship to colorectal cancers with micro‐satellite instability. Therefore, IELs might represent a new diagnostic tool for SSA‐D.

Prospective evaluation of endoscopic criteria characteristic of sessile serrated adenomas/polyps

BACKGROUND

Differentiating sessile serrated adenoma/polyp (SSA/P) from hyperplastic polyp (HP) is clinically important in determining the necessity of endoscopic resection or recommending appropriate surveillance. There are few reports of characterization of SSA/P using narrowband imaging and chromoendoscopy with and without magnification. We aimed to establish imaging criteria to aid real-time diagnosis of SSA/P.

METHODS

Patients with pale sessile or flat lesions of 6 mm or greater were prospectively enrolled in this multicenter trial. Nine endoscopic criteria, determined in real time, were investigated for possible association with SSA/P. Endoscopic mucosal resection was performed; specimens were retrieved and analyzed by histopathological examination.

RESULTS

In 63 patients, 89 lesions were detected, including 41 HP, 38 SSA/P, five mixed polyps, and five other lesions. Right-side colon location, lesion size of 10 mm or greater, excessive mucus, the presence of a varicose microvascular vessel (VMV) noted with high-magnification narrowband imaging, and type III(H) pit pattern were each commonly associated with SSA/P compared with HP. Multivariate analysis substantiated three independent endoscopic criteria for SSA/P: the presence of VMV (p = 0.001), lesion size of 10 mm or greater (p = 0.0017), and right-side location (p = 0.0041), with odds ratios of 8.2, 7.2, and 6.1, respectively. The presence of VMV had a significantly higher specificity (87.8%) than the other two independent endoscopic criteria (p = 0.0007 and p = 0.0008, respectively), but a lower sensitivity (57.9%), whereas a combination of the three criteria (two or more positive) increased the sensitivity significantly (89.5% and p = 0.0033) and had a higher degree of accuracy (82.3%).

CONCLUSIONS

Three endoscopic criteria individually and in combination were effective in predicting a diagnosis of SSA/P without the need for chromoendoscopy.