From the Guidelines
Sessile polyps can be either adenomatous or hyperplastic, and their management should be based on their histological classification rather than their physical appearance. The term "sessile" only describes the physical appearance of the polyp (flat, broad-based, without a stalk) rather than its histological classification. Adenomatous polyps are precancerous lesions that have the potential to develop into colorectal cancer over time, while hyperplastic polyps are generally considered non-neoplastic with minimal malignant potential. According to the study by Rex et al. 1, sessile serrated polyps (SSPs) are managed the same as adenomas, and their removal and surveillance are recommended. The distinction between adenomatous and hyperplastic polyps cannot be made reliably by visual inspection alone during colonoscopy and requires histological examination after removal. Adenomatous polyps typically show dysplastic changes in the epithelium with abnormal cell growth patterns, while hyperplastic polyps show elongated crypts with serrated architecture but without dysplasia. This distinction is clinically important because adenomatous polyps require more aggressive surveillance with follow-up colonoscopies at shorter intervals (typically 3-5 years depending on size, number, and histology), while isolated small hyperplastic polyps in the rectosigmoid region may not necessitate accelerated surveillance beyond routine screening intervals 1. Some hyperplastic polyps, particularly those that are large and sessile, may have atypical architectural and cytologic features and are at risk for progression to serrated adenoma and ultimately to sporadic MSI adenocarcinoma 1. Therefore, it is essential to remove and examine all sessile polyps to determine their histological classification and manage them accordingly.
From the Research
Sessile Polyps Classification
- Sessile polyps can be either adenomatous or hyperplastic, but recent studies have shown that they are more likely to be adenomatous, specifically a type of serrated adenoma known as sessile serrated adenoma/polyp (SSA/P) 2, 3, 4.
- SSA/Ps are characterized by their serrated morphology and are thought to progress to colorectal carcinoma via the serrated pathway, which involves epigenetic alterations and mutations in the BRAF oncogene 2, 4.
- The distinction between SSA/Ps and hyperplastic polyps (HPs) can be challenging, but studies have identified certain factors that are associated with an increased risk of an HP being reclassified as an SSA/P, including size ≥5 mm, proximal location, and synchronous adenomas with advanced pathology 5.
Molecular Features
- SSA/Ps are characterized by molecular features such as hypermethylation of CpG islands in gene promoters and activating point mutations in the BRAF oncogene, which are also seen in sporadic colorectal carcinomas with microsatellite instability (MSI) 4.
- The molecular signatures of SSA/Ps are distinct from those of traditional adenomas, and they are thought to play a key role in the development of a subset of colorectal cancers 3, 4.
Clinical Implications
- The classification of sessile polyps as SSA/Ps or HPs has important implications for clinical management, including surveillance intervals and the risk of malignant progression 6, 5.
- Studies have shown that SSA/Ps are more likely to be located in the proximal colon and are associated with an increased risk of colorectal carcinoma, highlighting the importance of accurate diagnosis and classification of these lesions 4, 6.