Poor diagnostic reproducibility in the identification of non-conventional dysplasia in colitis impacts the application of histological stratification tools.

Due to their increased cancer risk, patients with longstanding inflammatory bowel disease (IBD) are offered endoscopic surveillance with concomitant histopathological assessment, aimed at identifying dysplasia as a precursor lesion of colitis-associated colorectal cancer. However, this strategy is beset with difficulties and limitations. Recently, a novel classification criterion for colitis-associated low-grade dysplasia (LGD) has been proposed and an association between non-conventional dysplasia and progression reported, suggesting the possibility of histology-based stratification of patients with colitis-associated lesions. Here, a cohort of colitis-associated lesions was assessed by a panel of six experienced pathologists to test the applicability of the published classification criteria and to try and validate the association between non-conventional dysplasia and progression. While confirming the presence of different morphological patterns of colitis-associated dysplasia, the study demonstrated difficulties concerning diagnostic reproducibility between pathologists and was unable to validate the association of non-conventional dysplasia with cancer progression. Our study highlights the overall difficulty of using histological assessment of precursor lesions for cancer risk prediction in IBD patients and suggests the need for a different diagnostic strategy that can objectively identify high-risk phenotypes.