Background and study aim The World Health Organization criteria for SPS were established in 2010 and modified in 2019. Neither set of criteria have been validated against genetic markers or proven to be the optimal criteria for defining colorectal cancer risk in patients with serrated colorectal lesions. In this study, we sought to gain insight into how frequently the change in serrated polyposis syndrome (SPS) criteria in 2019 impacted the diagnosis of SPS. Materials and methods We reviewed 279 patients with SPS diagnosed between 2010 and 2019 using the 2010 criteria (n = 163) or since 2019 using the 2019 criteria (n = 116). We reviewed whether patients in each group met the diagnosis of SPS by the alternative criteria. Results Of those diagnosed using 2010 criteria, 5.5% did not meet 2019 criteria. Of those diagnosed by 2019 criteria, 10.3% did not meet 2010 criteria. Conclusions Most patients with SPS in our database met the diagnosis of SPS by both 2010 and 2019 criteria, with only 5-10% of patients in each cohort not meeting the alternative diagnostic criteria.

Background and study aims We anecdotally encounter cases where referring endoscopists made errors in endoscopic interpretation of a colorectal lesion, sometimes combined with pathology errors at the referring centers, resulting in referral to our center for endoscopic resection. In this paper, we describe the frequency and nature of endoscopic and pathology errors leading to consultation for endoscopic resection. Patients and methods Review of 760 consecutive referrals to our center over a 26 month interval. Results In total, 28 (3.7%) of all referred patients had ≥ 1 lesion that did not require any resection after investigation. There were 12 cases (1.6% of all referrals) involving errors by both the referring endoscopist and the pathologist at the referring center. Errors commonly involved the ileocecal valve, lipomas, and mucosal prolapse changes. There were 15 additional referrals (2.0% of all referrals) where no neoplastic lesion was identified at our center and either no biopsy was taken at the referring center (n = 9 patients, 10 lesions), the patient was referred although biopsy showed no neoplasia (n = 6), or the referring doctor correctly interpreted the lesion (lipoma), but the outside pathologist incorrectly reported adenoma (n = 1). Conclusions Endoscopists at tertiary centers should expect referrals to clarify the nature of colorectal lesions as neoplastic or non-neoplastic. Community endoscopists with equivocal endoscopic findings and unexpected or equivocal pathology results can consider pathology review at their center or at an expert center before referral for endoscopic or surgical resection.