Prevalence of nonpolypoid colorectal neoplasms in symptomatic patients scheduled for colonoscopy: a study with total colonic chromoscopy.

Objectives: (i) To determine the prevalence of nonpolypoid colorectal neoplasms (NP-CRNs) in a prospective cohort of patients of a Mediterranean area; (ii) to compare the characteristics of NP-CRNs with those of polypoid adenomas, focusing on the rate of high-grade dysplasia (HGD) and carcinoma; (iii) to evaluate the characteristics of patients harboring NP-CRNs versus patients with protruding adenomas (P-CRNs).

Patients And Methods: A prospective, cross-sectional observational study was made in which consecutive unselected patients were scheduled for colonoscopy and pancolonic chromoendoscopy. The Paris Classification of Superficial Neoplastic Lesions was used to classify the detected lesions, and the revised Vienna criteria were applied to describe the grade of dysplasia. All examinations were performed by the same endoscopist, and all samples were reviewed by the same pathologist.

Results: A total of 290 patients were included, and 613 neoplasms were detected-26% of them being NP-CRNs. The prevalence of NP-CRNs was 34.1% [95% confidence interval (CI): 28.8%-39.7%]. The proportion of HGD or carcinoma in NP-CRNs was 2.5% (95% CI: 0.8%-5.9%), versus 2.9% in P-CRNs (95% CI: 1.6%-4.7%). Size larger than 10 mm [odds ratio: 22.7 (95% CI: 5.2-99.2)] and a pedunculated morphology [odds ratio: 5.7 (95% CI: 1.3-24.3)] were related to the presence of HGD or carcinoma. A relationship between increased size and HGD or carcinoma was found for all morphologies. Patients harboring only NP-CRNs and patients harboring only P-CRNs were similar for all the variables collected.

Conclusions: NP-CRNs have a high prevalence in our region, but show a proportion of HGD and carcinoma similar to that seen in P-CRNs. No patient variable is predictive of the presence of a NP-CRN.