Introduction: A substantial interobserver variation in the differential diagnosis of hyperplastic polyps (HPs) and sessile or traditional serrated adenomas (SSAs/TSAs) has been described.
Methods: The aim of this study is to determine the magnitude of reclassification of HPs and associated factors after pathological reassessment of specimens from screening and surveillance colonoscopies, and to estimate its consequences for follow-up recommendations.
Results: Among 1694 screening and surveillance colonoscopies, a total of 536 polyps were initially diagnosed as HPs and remained unchanged in 88.5% (n = 474), whereas 7.6 (n = 41) and 1.1% (n = 6) were reclassified as SSA and TSA, respectively. Compared to definite HPs, SSAs were found more frequently in men than in women (82.9 vs. 61.2%, p < 0.05), and in individuals ≥65.0 years (51.2 vs. 31.6%, p = 0.05). Also, more SSAs were >5 mm in size (36.6 vs. 6.3%, p < 0.05) and were localized in the proximal colon (31.7 vs. 11.8%, p < 0.05). In a mixed model analysis, age ≥65.0 years (OR 4.13, 95% CI 1.22-14.2), snare polypectomy (OR 23.6, 95% CI 4.86-115), and coincident advanced adenomas (OR 7.56, 95% CI 1.31-43.5) were significantly (p < 0.05) associated with reclassification to SSAs. Only 0.53% of patients had received false recommendations for follow-up visits based on the incorrect HP diagnosis. A c.1799T>A, p.V600E BRAF mutation was detected in 21.9 % (n = 9) of reclassified SSAs.
Conclusion: Considering these factors may be helpful in serrated lesions that are difficult to allocate. Incorrect recommendations regarding control colonoscopy intervals due to misdiagnosed HPs can explain only a small fraction of interval colorectal cancers.
Keywords: Reclassification; Screening colonoscopy; Sessile serrated adenomas.