Colonoscopic surveillance in inflammatory bowel disease (IBD) is recommended to detect visible polypoid and nonpolypoid dysplasia (preferably with chromoendoscopy) and invisible dysplasia (with random biopsies). Low-grade dysplasia (LGD) is a risk factor for advanced colorectal neoplasia (ACRN: high-grade dysplasia or cancer); however, the significance of indefinite dysplasia (IND) is uncertain.
The authors performed a retrospective analysis of a cohort of patients with colonic IBD for 8 or more years or primary sclerosing cholangitis (PSC) who underwent surveillance at a tertiary center and had LGD, IND, or no dysplasia (NoD) on index colonoscopy. Their aims were to compare the risk of ACRN between patients with IND, NoD, and LGD. Multivariate adjustment was performed for risk factors for dysplasia, including PSC, disease extent, disease duration, histologic inflammation, and adequate surveillance colonoscopies.
Among 492 patients with 2149 person-years of follow-up, 53 (10.8%) had IND, 80 (16.3%) LGD, and 359 (73%) NoD. Chromoendoscopy was seldom used (2.5% of NoD and 6.4% of IND). Of lesions classified as LGD, 84% were visible (71% polypoid, 11% nonpolypoid, and 2% stricture). Of those with IND, only 18% were visible (ie, most were picked up with random biopsies). The incidence rate per person-year of ACRN with NoD was 0.4%, IND 3.1%, and LGD 8.4%. In IND patients, if dysplasia was not confirmed on a second procedure, the risk of ACRN was significantly lower (0.5% vs 9.9% per patient-year). On multivariate analysis, the risk of developing ACRN was higher with IND than NoD (HR, 6.85; CI, 1.78-26.4) and LGD than IND (HR, 3.14; CI, 1.02-9.62).
In a retrospective cohort in which chromoendoscopy was infrequently performed, IND, which was primarily detected on random biopsy, was an independent risk factor for ACRN. With more widespread application of optimal surveillance techniques, some/many of these invisible IND lesions may prove to be visible LGD. When IND is encountered on a random biopsy, repeat colonoscopy by an expert endoscopist and using chromoendoscopy should be considered.
Mahmoud R, Shah SC, Torres J, et al. Association between indefinite dysplasia and advanced neoplasia in patients with inflammatory bowel diseases undergoing surveillance. Clin Gastroenterol Hepatol
2019 Aug 22. (Epub ahead of print) (https://doi.org/10.1016/j.cgh.2019.08.032