The final diagnosis by P2 of the 300 polyps was: hyperplastic polyp (HP) (n = 71), serrated adenoma (SA) (n = 9), tubular (TA) (n = 45), tubulovillous (TVA) (n = 136) and villous adenoma (VA) (n = 12). There was 38 pT1 and 38 pTis carcinomas. 61 adenomas had high-grade dysplasia (HGD) and 72 had low-grade dysplasia (LGD). The initial diagnosis of HP was confirmed by P2 in 88.9% of cases, that of SA only in 15.1% of cases (87.1% of SA diagnosed by P1 were HP according to P2). The initial diagnosis of TA, TVA and VA was confirmed by P2 in respectively 29.1%, 75.6% and 26.7% of cases. The villous component had been overread in 12.2% of TVA and 60% of VA. It had been underread in 69.8% of TA and 6.7% of TVA. LGD was confirmed by P2 in 72% of cases. The initial diagnosis of HGD and pTis carcinoma was confirmed in 66.9% of cases. It had been overestimated by P1 in 27.1% of cases and underestimated in 5.1%. The initial diagnosis of pT1 carcinoma was confirmed in 84.2% of cases. It had been overestimated in 15.8% of cases. The diagnosis of pT1 carcinoma by P2 had been underestimated by P1 in 15.8% of cases. Overall, there was agreement between P1 and P2 for the assessment of type and dysplasia in 40.3% of cases, disagreement without any clinical impact in 11% and with an impact on management in 48.7% of cases, leading to inappropriate endoscopic surveillance intervals (too short n = 73; too long n = 68) or to unnecessary surgical resection (n = 2). The degree of differentiation of pT1 carcinomas was specified in 68.4% of cases, the resection line margin in 73.7% and the presence or absence of lymphatic invasion in 44.7% of cases.