Correlations of morphology and molecular alterations in traditional serrated adenoma

Clinical and endoscopic characteristics of colorectal traditional serrated adenomas with dysplasia/adenocarcinoma in a Korean population

BACKGROUND

Traditional serrated adenoma (TSA) is a rare and precancerous lesion of colorectal cancer. The clinical and endoscopic differentiations between TSAs without dysplasia or adenocarcinoma (TSAOs) and TSAs with dysplasia or adenocarcinoma (TSADs) remain unclear.

AIM

To evaluate the characteristics of colorectal TSAs and compare the characteristics of TSAOs with those of TSADs.

METHODS

This retrospective study included 193 patients who underwent endoscopic resection and received a pathologic diagnosis of TSA. We reviewed the medical, endoscopic, and histopathologic records of patients who underwent endoscopic resection of TSAs between January 2010 and December 2023.

RESULTS

TSAs were more frequently located in the rectosigmoid colon. Most TSAs had 0-Ip, 0-Isp, or 0-Is morphologies. The TSAD lesions were larger than TSAO lesions. TSAD lesions more commonly had a red color and an irregular border than TSAO lesions. TSAOs were usually treated using conventional endoscopic mucosal resection, whereas TSADs were treated using conventional endoscopic mucosal resection, endoscopic submucosal dissection, and surgery. Post-polypectomy bleeding was more common with TSADs than with TSAOs. Univariate analysis showed that gastrointestinal bleeding, red color, 0-IIa, irregular border, and lobular mucosal surface were significantly associated with TSADs. Multivariate analysis showed that gastrointestinal bleeding, an irregular border, and a lobular mucosal surface were significantly associated with TSADs.

CONCLUSION

TSAs with gastrointestinal bleeding, an irregular border, and a lobular mucosal surface are associated with an increased risk of dysplasia or adenocarcinoma.

The histologic features, molecular features, detection and management of serrated polyps: a review

The serrated pathway to colorectal cancers (CRCs) is a significant pathway encompassing five distinct types of lesions, namely hyperplastic polyps (HPs), sessile serrated lesions (SSLs), sessile serrated lesions with dysplasia (SSL-Ds), traditional serrated adenomas (TSAs), and serrated adenoma unclassified. In contrast to the conventional adenoma-carcinoma pathway, the serrated pathway primarily involves two mechanisms: BRAF/KRAS mutations and CpG island methylator phenotype (CIMP). HPs are the most prevalent non-malignant lesions, while SSLs play a crucial role as precursors to CRCs, On the other hand, traditional serrated adenomas (TSAs) are the least frequently encountered subtype, also serving as precursors to CRCs. It is crucial to differentiate these lesions based on their unique morphological characteristics observed in histology and colonoscopy, as the identification and management of these serrated lesions significantly impact colorectal cancer screening programs. The management of these lesions necessitates the crucial steps of removing premalignant lesions and implementing regular surveillance. This article provides a comprehensive summary of the epidemiology, histologic features, molecular features, and detection methods for various serrated polyps, along with recommendations for their management and surveillance.

Pathologic Features of Primary Colon, Rectal, and Anal Malignancies

In USA, colorectal cancer is the third most commonly diagnosed cancer in men, second in women, as well as the third leading cause of cancer deaths (Siegel et al. in Cancer J Clin 73:1-112, 2023 [109]). Worldwide, colorectal cancer is the second leading cause of death and causes almost 916,000 deaths each year (Ferlay in Global cancer observatory: cancer today. International Agency for Research on Cancer, Lyon, 2020 [28]). Fortunately, due to the colon's surgical and endoscopic accessibility and functional redundancy, colorectal cancer is very treatable. Colonoscopic surveillance has the potential for not only providing tissue for the diagnosis of precancerous polyps and invasive carcinoma, but also preventing development of invasive carcinoma by the removal of precancerous lesions. This chapter discusses the clinical and pathologic features of the spectrum of epithelial, hematolymphoid, and mesenchymal malignant tumors of the colon, rectum, appendix, and anus.

An incidental traditional serrated adenoma of the gallbladder: A case report

Serrated lesions outside the low digestive tract are scarce, with only two traditional serrated adenomas (TSA) reported in the gallbladder, with limited information about the serrated pathway outside the colon. Our case was an incidental finding in a patient undergoing surgery to treat a cholecystitis, when a polypoid lesion was observed. The epithelium formed gland structures with ectopic crypts, serrated slits and eosinophilic cytoplasm. MUC4 and MUC5A were positive, but mismatch repair proteins (MSI) retained nuclear staining. BRAF showed a not mutated profile and NRAS/KRAS was inconclusive due to the absence of remaining tissue. MSI and CpG island (CIMP), the most common genetic hallmarks of the serrated pathway, have been proven in gallbladder carcinomas, although serrated polyps are not recognized as premalignant precursors. Hereby we report one TSA of the gallbladder without the usual genetic drivers. A larger evidence is needed to improve the diagnosis and management.

Traditional Serrated Adenoma of the Urinary Bladder: The First Report

A 71-year-old woman was hospitalized with hematuria and underwent cystourethroscopy. Cystourethroscopy revealed a polypoid bladder tumor. Histopathologic examination showed complex villiform growth pattern, slit-like serrations, and ectopic crypts lined by epithelium with eosinophilic cytoplasm, pseudostratified elongated nuclei, consistent with traditional serrated adenoma. Nephrogenic and intestinal metaplasia with severe inflammation were present in adjacent bladder mucosa. Molecular study of the polyp revealed mutation (p.G12V) in codon 12 of exon 2 of the KRAS gene. Traditional serrated adenoma is a rare type of colonic serrated polyp, making up less than 1% of the colonic polyps with a predilection to distal colon. In the literature, there is no traditional serrated adenoma reported outside the gastrointestinal tract. Here in we report the first extra-gastrointestinal traditional serrated adenoma within the bladder and bladder diverticulum, arising from intestinal metaplasia. The present study reports an additional information on molecular background of this unusual bladder polyp.

Comprehensive analyses of microRNA and mRNA expression in colorectal serrated lesions and colorectal cancer with a microsatellite instability phenotype

MicroRNA (miRNA) expression is dysregulated in human tumors, thereby contributing to tumorigenesis through altered expression of mRNA. Thus, identification of the relationships between miRNAs and mRNAs is important for evaluating the molecular mechanisms of tumors. In addition, elucidation of the molecular features of serrated lesions is essential in colorectal tumorigenesis. Here, we examined the relationships of miRNA and mRNA expressed in serrated lesions, including 26 sessile serrated lesions (SSLs), 12 traditional serrated adenomas (TSAs), and 11 colorectal cancers (CRCs) with a microsatellite instability (MSI) phenotype using crypt isolation. We divided the samples into the first and second cohorts for validation. Array-based expression analyses were used to evaluate miRNAs and mRNAs with opposite expression patterns in isolated tumor glands. In addition, we validated the relationships of miRNA/mRNA pairs in the second cohort using real-time polymerase chain reaction. We found that the expression of miRNA-5787 was correlated with reciprocal expression of two mRNAs, that is, SRRM2 and POLR2J3, in SSL samples. In TSA samples, two pairs of miRNAs/mRNAs showing opposite expression patterns, that is, miRNA-182-5p/ETF1 and miRNA-200b-3p/MYB, were identified. Ultimately, three pairs of miRNAs/mRNAs with opposite expression patterns, including miRNA-222-3p/SLC26A3, miRNA-6753-3p/FABP1, and miRNA-222-3p/OLFM4, were retained in CRC with an MSI phenotype. Finally, we performed transfection with an miR-222-3p mimic to confirm the expression of SLC26A3 and OLFM4; the results showed that ectopic expression of miR-222-3p moderately suppressed OLFM4 and downregulated SLC26A3 to some extent. Overall, our results provided basic insights into the evaluation of colorectal tumorigenesis of serrated lesions and CRC with an MSI phenotype.