Examination of non-conventional dysplasias adjacent to colorectal adenocarcinoma in patients with IBD.

Objective: Recently, several non-conventional variants of IBD-associated dysplasia have been described; however, their prevalence in Central-Eastern Europe is unknown. We aimed to perform a retrospective pilot study by re-evaluating several IBD-associated adenocarcinoma cases to survey the incidence of adjacent non-conventional dysplasia and validate that recent North American findings may apply to a European population. Methods: Retrospectively, 28 randomly chosen cases of IBD-associated adenocarcinomas diagnosed between 2010 and 2022 were re-evaluated. The patient's sex, age (at the diagnosis of IBD and neoplasia), type of IBD, type of specimen [biopsy (n = 8)/surgical specimen (n = 20)], histological type, grade, localisation, stage, disease-free (DFS) and overall survival (OS) were obtained. Statistical analyses were carried out by using Mann-Whitney (continuous variables), Fisher's exact (categorical variables), Kaplan-Meier (DFS/OS curves), and logrank test (survival curves). Results: Exclusively, conventional dysplasia was observed in 11, and non-conventional dysplasia in 8 patients. Combined conventional and non-conventional dysplasia was detected in 9 patients. Non-conventional dysplasia showing a combination of multiple subtypes was noted in 10 cases. Altogether, 25 non-conventional dysplastic foci were identified, which were diagnosed as hypermucinous (n = 9), goblet cell-deficient (n = 6), serrated not otherwise specified (NOS) (n = 6), and traditional serrated adenoma-like (n = 4). The majority of non-conventional dysplasias were associated with ulcerative colitis (n = 12). Mucinous adenocarcinoma was exclusively associated with non-conventional dysplasia, while medullary carcinoma was only with conventional dysplasias ( Conclusion: Based on our results, non-conventional dysplasia is common (60%) adjacent to IBD-associated adenocarcinomas in a Central-Eastern European population and may be detected in biopsies. As multiple recent publications reported evidence of a worse prognosis and more common flat morphology compared to conventional dysplasias, their recognition is of great importance, and stricter follow-up with random biopsy samples may be considered.