ECP 2023 Abstracts

S95 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 ß-catenin and L1CAMwas confirmed as an independent prognostic factor affecting recurrence (p=0.004) along with FIGO stage (p=0.001). Conclusion: We showed that ß-catenin expression could stratify no spe- cific molecular profile group by identifying EC patients with higher risk for severe outcomes and L1CAM expression could stratify p53 abnormal subgroup by identifying EC patients with more favourable prognosis. Thus, we propose the modified molecular classification that integrates the ß-catenin expression within NSMP subgroup and L1CAM expression within p53 abnormal subgroup into the ProMisE classification. PS-11 | Poster Session Haematopathology PS-11-001 Correlation between tumour infiltrating lymphocytes and prognostic factors in mantle cell lymphoma J. Chabla Jaramillo*, A. Diazgranados Daza, J.T. Zuñiga Gaitan, M. Diaz Guillen, S. Ramón y Cajal Agüeras, J. Castellvi Vives *Hospital Universitari Vall d’Hebron, Spain Background & objectives: In mantle cell lymphoma (MCL) there are variable numbers of T cells admixed with tumour cells which role in its behaviour is not well known. Therefore, we wanted to know if they correlate with known morphological prognostic factors. Methods: We selected 37 lymph nodes with MCL from the files of our department, and the morphologic type, p53 immunohistochemistry result and ki67 expression were recorded. To quantify TILs, CD3 immunohisto- chemical slides were scanned and evaluated with the cell quant algorithm of 3D-Histech QuantCenter, and the results were analysed with SPSS. Results: The series was composed of 32 classic and 5 blastoid MCL. Only one of theme showed overexpression of p53. Ki67 cases were grouped in cases with <30% (17 cases) and >30% (20 cases) of positive cells. The number of TILs varied from 177% to 7% of the total cells. This result correlated with Ki67, with higher number of TILs in Ki67 low cases (p=0.044). No correlation was found with morphologic variants. Conclusion: Although it is a short series of MCL, there is a correlation of TILs and one of the most used prognostic factors in MCL. Interestingly, the cases with higher TILs showed less proliferation index, and therefore better prognosis. The case p53 positive was the one with more TILs of the series, but a larger series is necessary to evaluate if there is a correla- tion between them. PS-11-002 High level of tumour-infiltrating T lymphocytes predicts better prognosis in diffuse large B-cell lymphoma Y. Cho*, J. Cho *Department of Pathology and Translational Genomics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Republic of Korea Background & objectives: The implication of tumour-infiltrat- ing T lymphocytes (TIL-T) in diffuse large B-cell lymphoma (DLBCL) is yet to be elucidated. We aimed to investigate the effect of the degree of TIL-T on the prognosis of DLBCL patients. Methods: Ninety-six patients with DLBCL, not otherwise specified were enrolled in the study. The ratio of TIL-T was measured as the ratio of CD3-positive cells to total cells using QuPath, a digital pathology software. The TIL-T ratio was investigated in three foci (high, interme- diate, and low) in each case and the relationship between TIL-T ratio and overall survival was investigated. Results: Among 96 patients, 44 (45.8%) were Ann Arbor stage III-IV, and 64 (66.7%) were non germinal centre B-cell in cell-of-origin. When a TIL-T ratio of 25% was used as the cutoff value, high TIL-T and low TIL-T patients were 62 (64.6%) and 34 (35.4%), respectively. High TIL-T ratio was significantly associated with lower Ann Arbor stage (p=0.011). Upon univariate analysis, patients with low TIL-T ratio had a significantly worse prognosis in overall survival compared to those with high TIL-T ratio (p<0.001); this difference remained significant in a multivariate analysis with Cox proportional hazards (hazard ratio, 6.52; 95% confidence interval, 2.30 to 18.51; p<0.001). Conclusion: DLBCL patients with high TIL-T ratio showed a signifi- cantly better prognosis than those with low TIL-T ratio, and the level of TIL-T ratio was an independent indicator for overall survival. These results suggest that TIL-T may play a critical role in the disease progres- sion of DLBCL and evaluating the degree of TIL-T in DLBCL specimen using digital pathology software may become useful in predicting the clin- ical behaviour and the response to immunotherapy in DLBCL patients. PS-11-003 Molecular classification of systemic diffuse large B-cell lymphoma in Korea Y.A. Kim*, J. Yim, B. Han, S. Lim, Y.K. Jeon *SMG-SNU Boramae Medical Center, Republic of Korea Background & objectives: Diffuse large B-cell lymphoma(DLBCL) features medium to large B-cells with a diffuse growth pattern, diverse morphology and molecular profiles. This study aimed to categorize sys- temic DLBCL in Korea via the LymphGen classifier and analyse distinct clinicopathological features of each subgroup. Methods: We conducted customized targeted gene sequencing for 121 lym- phoma-related genes and immunohistochemistry in 151 systemic DLBCL patients including EBV+ DLBCL, THRLBCL, PMBL, and IVLBCL. For 135 DLBCL, NOS cases, clinical data, including gender, age, symp- toms, serum LDH level, stage, IPI risk group, and treatment response were obtained. We analysed clinicopathologic and molecular differences and outcomes according to the LymphGen subgroups. Results: DLBCL, NOS were categorized into MCD(23%), A53(17%), EZB(9%), BN2(6%), and unclassified ("Other")(39%) by LymphGen clas- sifier. EBV+ DLBCL were classified as ST2 and other subgroups, while TCRLBL as MCD and other subgroups, and all PMBL were unclassifiable. The BN2 had a higher proportion of older patients, and the EZB had higher GCB subtype proportion. The A53 frequently showed mutations in TP53, and IRF4; EZB exhibited mutations in BCL2, MYC, KMT2D, SGK1, and EZH2; MCD showed mutations in PIM1, BTG1, CD79B, HIST1H1E, MYD88, and PRDM1; ST2 exhibited mutations in ITPKB and SOCS1, mostly consistent with previous studies. In the unclassified ("Other") group, frequent mutations were observed in TET2, KMT2C, PIM1, and IRF4. Conclusion: This study classified systemic DLBCL cases in Korea using the LymphGen classifier and analysed the unique clinicopathological char- acteristics of each subgroup. The distribution of the LymphGen subgroups varied among different types of DLBCL. The identification of specific mutations in each subgroup, which were largely consistent with previous studies, indicates that the LymphGen classifier may be valuable in indi- vidualized treatment approaches for DLBCL patients. Additionally, this study demonstrates that unclassified group ("Other") may potentially be established as a distinct subgroup. PS-11-004 NGS testing practices and molecular profile of KIT in systemic mastocytosis: real-world insights from France, Italy, and Spain N. Lamontagne*, S. Cheloni, S. Lima, T. Green, Z. Crouch, A. Kim *Blueprint Medicines, Switzerland Background & objectives: ~95% of systemic mastocytosis (SM) cases are driven by the KIT D816V mutation (Ungerstedt, et al. Cancers. 2022;14(16):3942). We examine next-generation sequencing (NGS) KIT testing practices in France, Italy, and Spain to investigate molecu- lar profiles potentially associated with SM cases. Methods: The SOPHiA DDM™ Platform (SOPHiA GENETICS SA, Switzerland) was used to analyse pseudonymized real-world genomic