ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 as follows: 8 gastric-antrum, 2 gastric-cardia, 2 ampullary- duodenum, 10 ascending colon, 2 transvers colon. On micro- scopic examination of tumours the most prominent feature that attracted our attention was that majority of the cases (20 out of 24) formed at least focal crypt-like structures formed by signet ring-like cells in either myxoid(mostly) or desmoplas- tic stroma. Remaining 4 cases showed conventional intestinal carcinoma morphology with amphicrine immunophenotype. Another significant finding was the presence of multiple lymph node metastases and advanced stage disease in all of the cases, except for four cases. Conclusion: Despite the fact that this entity is not included in the current WHO classification of GI organs other than appendix, they usually present in advanced stages and exhibit aggressive behav- iour. In most, if not all, amphicrine tumours have characteristic morphologic clues (crypt-like structures formed by signet-ring-like cells) and clinical features(83% of the lower-GI cases on ascending colon). These clues can be defined clearly, and the terminology should be used in daily practice in order to assure an adequate therapy in a timely manner. OFP-01-011 Mismatch repair protein and microsatellite instability status in gastric cancer: a comparative study between endoscopic biopsies and surgical specimens I. Gullo*, D. Sousa Marques, J. Ricardo Silva, L. Mascarenhas- Lemos, X. Wen, C. Nascimento, A. Costa, A. Faria, C. Gouveia, L. Pinho, P. Patrícia, M. Cravo, F. Carneiro *Department of Pathology, Centro Hospitalar Universitário de São João; Faculty of Medicine of University of Porto (FMUP); i3S - Instituto de Investigação e Inovação em Saúde da Universidade do Porto, Portugal Background & objectives: Evaluation of mismatch repair protein (MMR) and microsatellite instability (MSI) status is of utmost importance for the management of gastric cancer (GC) patients. Aim: to assess if MMR/MSI-status in surgical specimens (SSs) may be predicted accurately in endoscopic biopsies (EBs). Methods: One-hundred GC cases with EBs and respective SSs were selected retrospectively from two institutions between 2004 and 2015. Both EBs and SSs were evaluated for MMR-status by immunohistochemistry (IHC) and classified as MMR-proficient (MMRp) or deficient (MMRd). Cases were also classified for MSI- status by Idylla TM and Bethesda panel (five mononucleotide mark- ers) as microsatellite stable (MSS) or unstable (MSI-high). Results: Sixty-three patients were submitted to surgery alone, while 37 patients underwent neoadjuvant chemotherapy. In SSs, 64/100 cases (64%) were MMRp and 36/100 (36%) were MMRd by IHC; 72/100 (72%) were MSS and 28/100 (28%) were MSI-high by Idylla TM . In SSs, no cases classified as MMRp were MSI-high, but 21/100 cases (21%) were reported as MMRd by IHC and MSS by Idylla TM . MSI-status, evaluated by Idylla TM , was concordant to the gold-standard Bethesda panel in 64/65 SSs (98.5%). When comparing EBs and SSs, only 5/100 cases (5%) were discordant by IHC (k=0.889%, sensitivity=88.9%, specificity=98.4%), while 14/100 cases (14%) were discordant by Idylla TM (k=0.620, sensitiv- ity=60.1%, specificity=95.8%). Conclusion: High concordance rate was found when comparing EBs and SSs for MMR-status by IHC, suggesting that we can rely on the immunohistochemical evaluation of EBs when assessing GC cases before surgery/neoadjuvant chemotherapy. The few discord- ant cases (n=5) may be explained by insufficient tumour sampling to account for GC heterogeneity (4/5 had ≤2 EBs), and/or neo- adjuvant chemotherapy (used in 3/5 patients). Although Idylla TM reliably evaluated MSI-status in SSs, as compared to gold-standard, it doesn’t seem to accurately identify MSI-status in EBs. Funding: Bolsas de Investigação Luz Saúde, Portugal OFP-01-012 Which is which? Autoimmune ( H. pylori ) gastritis N. Aras*, E.K. Çagdas, S. Kurt, B. Savas, A. Ensari *Ankara University Department of Pathology, Turkey Background & objectives: Pyloric metaplasia(PM) and neuroen- docrine-cell hyperplasia(NCH) are common features of autoim- mune gastritis(AIG), but are also seen in HP-gastritis leading to diagnostic difficulty. Co-ocurrence of two complicates their dis- tinction. We aimed to evaluate features useful in the differential diagnosis when overlaps occur. Methods: Total of 123 cases of gastritis comprising 77 AIG cases(group1) with normal/reactive antrum, 30 cases of HP-gas- tritis with concurrent atrophy and metaplasia in the corpus and antrum(group 2), and 16 cases with AIG-like changes in the cor- pus, and atrophy and/or IM in the antrum(group 3) were reevalu- ated for updated Sydney parameters, PM and NCH. Chi-square test was used for statistics. Results: Though all cases in group1 and 3 had inflamed cor- pus, severe chronic inflammation was significantly (p=0.03) higher in group 1(71.4%) compared to group3(37%) while activ- ity of group3(43.7%) was significantly higher (p<0.001) than group1(25,8%). Atrophy was significantly (p=0.026) higher in group2(86.6%) than group3 (50%) similar to IM (100% and 93,75 in groups 2 and 3, %, respectively). NCH was present in 80,5% of all cases and was significantly more common (p<0.001) in group3(100%) than group2(23.3%). PM, on the other hand, was seen in %77 of all cases and its frequency was significantly higher(p=0.002) in group1 (%85.7) compared to groups 2 and 3 (56.6%, 75%, respectively). Conclusion: Inflammation, both active and chronic, not differing between HP-gastritis with(group3) or without(group2) features of AIG, suggest that overlaps do indeed exist. As expected, IM and atrophy were more severe in HP-gastritis compared to HP-gastritis with features of AIG in contrast to NCH and PM which were more predominantly observed in AIG or HP-gastritis with such features. These, taken together, support the idea of incorporating PM and/ or NCH into the Sydney system of gastritis for accurate diagnosis, treatment of overlapping cases. OFP-01-013 Systemic neutrophil-to-lymphocyte ratio in colorectal cancer: differences in systemic cytokine profile and immune effector cell populations D. Bhattacharjee*, M. Cummings, N. Orsi, M. Cullen, S. Richards, R. Prasad, D. Jayne, P. Quirke, J. Pine *Pathology and Data Analytics, Leeds Institute of Medi- cal Research, School of Medicine, University of Leeds, United Kingdom Background & objectives: A raised pre-operative neutrophil- to-lymphocyte ratio (NLR) is correlated with poorer outcomes in colorectal cancer (CRC). We assessed the plasma cytokine pro- files and immune effector cell populations of NLR<5 and NLR>5 groups in operable CRC to establish a mechanism for this. Methods: Patients undergoing elective bowel resection for CRC were prospectively recruited. Preoperative plasma from 47 patients underwent cytokine analysis by multiplex fluid-phase immu- noassay. A second group of 33 patients was recruited for flow S4