Hyperplastic polyp? Look again... the impact of the new classification for serrated polyps

Area of Science:

• Gastroenterology
• Pathology
• Oncology

Background:

• The 2010 World Health Organization (WHO) classification introduced 'sessile serrated adenoma' as a distinct entity for serrated colonic polyps.
• This new classification recognizes the malignant potential of serrated lesions, necessitating a review of existing polyp diagnoses.
• The impact of this revised classification on polyp reclassification rates and clinical practice remains to be fully assessed.

Purpose of the Study:

• To determine the proportion of colonic polyps reclassified under the 2010 WHO guidelines.
• To identify factors influencing the reclassification of polyps, particularly hyperplastic polyps.
• To evaluate the clinical relevance of the revised classification for serrated polyps.

Main Methods:

• A retrospective review of all polyps resected over a 5-year period from patients with at least one diagnosed sessile serrated adenoma.
• Collection of data on polyp characteristics and patient variables.
• Analysis of 247 polyps from 40 consecutive patients.

Main Results:

• Of 247 reviewed polyps, 42% were hyperplastic, 29% conventional adenomas, 24% sessile serrated adenomas, and 5% serrated adenomas.
• Sixty-three polyps (25.5%) were reclassified, with a significant proportion of hyperplastic polyps (41% of 104) being reclassified as sessile serrated adenomas.
• Reclassification of hyperplastic polyps was independent of location but more likely if the polyp size was ≥ 5 mm.

Conclusions:

• The 2010 WHO classification leads to a substantial reclassification of hyperplastic polyps into sessile serrated adenomas.
• This highlights a potential underestimation of the serrated pathway in colorectal carcinogenesis.
• Current surveillance strategies may need adjustment for patients with reclassified serrated polyps.