Impact of reassessment of colonic hyperplastic polyps by expert GI pathologists

Recommended follow-up intervals after endoscopic removal of hyperplastic polyps (HP) and sessile serrated adenomas (SSA) differ because of assumed differences in biological behaviour. However, histopathologic differentiation is difficult, with higher SSA rates reported from specialist GI histopathologists.

The objective of this study was to clarify the relevance of histologic reassessment of HP.

From a prospective screening colonoscopy study relevant serrated lesions (excluding distal small HP ≤5 mm) diagnosed by private practice pathologists were reassessed by four specialized GI pathologists

One thousand sixty-nine screening colonoscopies were performed in patients.

In terms of main outcome measurements, there is a likelihood of changes of the HP diagnosis on reassessment, as well as interrater variability.

SSA were initially diagnosed in 7 cases (0.7%) and relevant HP in 83 (7.8%; 101 lesions). Of the latter, the chance of a change in diagnosis from HP to SSA by any of the four specialist histopathologists was higher for larger (>5 mm) and right-sided lesions (19.1 vs 1.3%, OR 18.4, p = 0.04) including a higher likelihood to change recommended follow-up intervals (32.1 vs 3.3%, p < 0.01). However, follow-up intervals were determined by concomitant adenomas in 41%. Interrater variability was also higher for these lesions (p = 0.04), with an overall kappa value of 0.48. However, this issue related to only 1.2% of the 1069 study cases.

The limitations this study are the limited case number as well as limited retrospective assessment.

Right-sided HP >5 mm had a higher chance of change in diagnosis to SSA; therefore, they should probably be treated like adenomas and be removed. However, reliable data for recommendations on follow-up intervals of HP or SSA will require follow-up studies.