Molecular characterization of visible low-grade dysplastic lesions in patients with inflammatory bowel disease

We studied pathogenic gene mutations and tumor mutation burden (TMB) in visible low-grade dysplastic lesions in patients with inflammatory bowel disease (IBD). The dysplastic lesions with histologically normal mucosa in the background (group 1) were compared with dysplastic lesions occurring either in a background of chronic active colitis (group 2) or associated with synchronous carcinomas regardless of the status of the background mucosa (group 3). The TMB in group 3 was consistently higher in comparison to the group 1 and group 2 lesions, although the difference was not statistically significant. There also seem to be different mutation profiles between the groups, indicating different pathways of tumor pathogenesis. More frequent APC mutations were seen in group 1 as compared to other groups and TP53 mutations were seen in groups 2 and 3, but none in group 1. Molecular characterization could potentially be used as an ancillary prognostic marker in challenging cases to guide the further management of IBD patients with visible dysplastic lesions.