ECP 2023 Abstracts

S108 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 System. The type of IM, presence of spasmolytic polypeptide-expressing metaplasia (SPEM) and dysplasia were also recorded. Results: Atrophy was observed in 41 (95%) of the oxyntic mucosa sam- ples; 7 mild (16.3%), 20 moderate (46.5%) and 14 severe (32.5%). IM and SPEM were detected in 30 (69%) and 5 (11%) cases, respectively. The presence of incomplete IM was found to be significantly low com- pared to complete intestinal metaplasia (n=12 vs n=27). Among cases with incomplete IM, it was focal and seen in addition to severe com- plete IM in 8 cases (66.6%). A statistically significant relationship was found between the degree of atrophy and the presence of incomplete IM (p=0.01). No dysplasia was detected in any of the cases. Conclusion: Our study revealed that despite the presence of widespread atrophy in HP(-)AIG cases, incomplete IM was observed at lower rates. Considering the association of incomplete IM with GACa in previous publications, our study suggests that the low risk of GACa in HP(-)AIG can be explained by the low prevalence of incomplete IM. On the other hand, it may show that gastric atrophy may not be the main determinant of gastric carcinogenesis in these cases. In conclusion, the follow-up of HP(-)AIG patients may deserve a different approach. PS-17-019 mRNAs, lncRNAs and circRNAs as prognostic biomarkers in stage II colon cancer U. Korsgaard*, J. Luis Garcia Rodriguez, J. Kjems, H. Hager, L. Som- mer Kristensen *Department of Pathology, Lillebaelt Hospital, University Hospital of Southern Denmark, Denmark Background & objectives: Treatment of stage II colon cancer is a clin- ical dilemma and despite treatment, a considerable number suffer from recurrence of disease. We aim to determine differentially expressed mRNAs, lncRNAs and circRNAs that can predict prognosis of stage II colon cancer. Methods: We performed total RNA sequencing on fresh frozen tissue from a cohort containing 59 patients. DESeq2 was used to detect dif- ferentially expressed mRNAs, lncRNAs and circRNAs between stage II colon cancer patients with and without recurrence. Receiver operating characteristics (ROC) analysis was used to determine the biomarker potential of individual RNAs in stage II colon cancer. Results: In the cohort, 29 patients suffered from stage II colon cancer and 11 of these had recurrence of disease. Using total RNA sequencing, we found 135 differentially expressed mRNAs, 77 differentially expressed lncRNAs and 4 differentially expressed circRNAs between stage II colon cancers with and without recurrence (p-adjusted < 0.05). For mRNA, ROC-analysis showed that PPP1R12A, MRLP30 and UBX2NA had an area under the curve (AUC) of 0.95, 0.93 and 0.92, respectively. For lncRNAs, ROC-analysis showed that HSD17B1-AS1, LOC100129931 and AFAP1-AS1 had an AUC of 0.91, 0.91 and 0.894, respectively. For circRNAs, ROC-analysis showed that circ_SRPK1, circ_MVP and circ_CCDC9 had an AUC of 0.88, 0.83 and 0.82, respectively. Conclusion: In this study, we found multiple promising and previously undescribed potential prognostic biomarkers in colon cancer. Our data suggest that mRNAs, lncRNAs and circRNAs can be used to distin- guish patients with high risk of recurrence in stage II colon cancer, and thus improve decision making when selecting patients that should receive adjuvant chemotherapy. However, further validation is needed to support our findings. The work was supported by the Region of Southern Denmark and the Research Council of Lillebælt Hospital. PS-17-020 Childhood florid reactive lymphoid follicular hyperplasia: a poten- tial diagnostic pitfall of a rare disease D. Laguna*, M.A. Martínez, C. González, C. Calvo, O. Moya, I. Amengual *Hospital Universitari Son Espases, Spain Background & objectives: Childhood florid reactive lymphoid fol- licular hyperplasia (CFRLFH) is a benign lymphoid proliferation that could be mistakenly diagnosed as a lymphoproliferative disorder. The aim of this study is to review the cases in our institution and to make a comparative analysis. Methods: All the cases diagnosed as CFRLFH in the last 15 years at our institution were selected by database consultation of our infor- matic program. Furtherly, sex and age, as well as clinical presentation and development, location, endoscopic imaging data, histopathology, immunohistochemical profile and IgH rearrangement results were noted. Results: A total of 4 cases of CFRLFH were finally recovered: two of them in appendix and the other two in rectum. All 4 cases showed histologically a B-type follicular hyperplasia with large and irregular germinal centre formation, located in submucosa with focal affecta- tion of mucosa, positive for CD20, CD10 and bcl-6 and negative for bcl-2. All cases displayed Lambda light chain restriction (by immuno- histochemistry and in situ hybridization); nonetheless, the molecular rearrangement of IgH showed policlonality. The age ranged between 4 and 6 years, with male predominance (3:1). Endoscopically, it was found one case with concomitant oxyurasis. Conclusion: CFRLFH is a rare disease with unknown aetiology, and histologically may be confused with malignant lymphoid processes such as paediatric-type follicular lymphoma (amongst others). Light chain restriction is not necessarily linked to monoclonality and may lead to misdiagnosis. Therefore, an appropriate clinical context is needed for the correct diagnosis: paediatric patients with consistent clinical, histological and immunohistochemical findings, as well as an indolent development. PS-17-022 Epigenetic regulation of CDX2 in colorectal cancer cell motility and tumour budding R. Mehmeti*, N. Bodmer, M.P. Tschan, I. Zlobec *Institute of Tissue Medicine and Pathology, University of Bern, Switzerland Background & objectives: CDX2 expression in colorectal cancer (CRC) predicts patient outcome and is often lost in tumour cell dis- semination and budding. We examine potential inhibitory effects of histone deacetylase (HDAC) family members on CDX2 expression, cell migration, epithelial-mesenchymal transition (EMT) and budding. Methods: Pharmacological and genetic inhibition of HDACs was applied to CDX2 negative CRC cells. We used CRISPR technology to knock out CDX2 in CDX2 positive CRC cell lines. These cells were evaluated using transwell migration and in ovo assays. Using multiplex immunofluorescence (mIF) we determined CDX2, HDAC and EMT marker expression in primary CRC patient samples. Results: Our HDAC pharmacological inhibitory screen identified UFO10, an HDAC class I and IIb inhibitor, as a dose dependent CDX2 activator. Using RNAi to validate CDX2 activation revealed HDAC 2,6, and 8 as potential CDX2 repressors. These cell lines and CDX2 knockout CRC cell lines showed decreased or increased cell migration, respectively. The chick embryo chorioallantoic membrane (CAM) in ovo assay showed increased invasiveness and tumour budding in CDX2 knockout compared to control cells. mIF analysis showed significantly lower CDX2 and EMT marker levels associated with aberrant HDAC class I/IIb expression in tumour buds compared to nearest primary tumour regions in primary CRC patient samples. Conclusion: Our study highlights CDX2’s critical role in CRC pro- gression and metastasis. We identified HDAC 2, 8 (class I), and 6 (class IIb) as CDX2 repressors. Low CDX2 expression increases CRC cell migration as well as tumour cell dissemination and is associated with tumour budding and EMT in primary CRC patients. Our findings