Prevalence of advanced histologic features in diminutive colon polyps

Accurate in vivo differentiation of colon polyp histology may serve to prevent the resection of diminutive hyperplastic polyps in the distal colon or the need for histologic assesment of diminutive polyps after resection. The clinical implementation of these strategies depends on the prevalence of advanced histologic findings among diminutive polyps. We aimed to determine the prevalence of advanced histologic features (villous features, high-grade dysplasia, and adenocarcinoma) in diminutive colon polyps and compare it to small and larger polyps.

The data of patients who had undergone elective colonoscopy at a tertiary-care referral center were retrospectively reviewed. The size, morphology, and location of all polyps were recorded. Polyps were divided into 3 groups according to their size: diminutive (≤ 5 mm), small (6-9 mm), and large (≥ 10 mm).

A total of 7160 polyps in 3226 eligible patients were evaluated. The mean diameter of the polyps were 6.7 ± 4.9 mm. Histopathologic diagnosis were adenomatous in 4548 (63.5%) and non-adenomatous in 2612 (36.5%). Out of 7160 polyps, 4902 (68.5%) were diminutive (1-5 mm), 1360 (19%) were small (6-9 mm), and 898 (12.5%) large (≥ 10 mm) polyps. Among the diminutive polyps 2739 (55.9%) had adenomatous histology. There were 66 polyps (1.3%) with advanced histology in the diminutive group, 72 (5.2%) in the small group, 263 (29.2%) in the large polyp group. Diminutive polyps had a lower frequency of advanced histology compared to small and large polyps (p = 0.001). When the histology of the polyps were evaluated based on the size of the largest polyp the patient has, 2202 patients had polyp(s) ≤ 5 mm. The frequency of advanced histology was 2.2% in these patients.

The prevalence of advanced histology in diminutive polyps is quite low (1.3%) which supports the clinical implementation of discard, resect and discard strategies in diminutive polyps.