ECP 2023 Abstracts

S275 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 Echocardiography reveals asymmetric hypertrophic cardiomyopathy that on MRI implies biventricular involvement. Biopsy is performed by cardiac catheterization. Results: Tissue fragments are received where infiltration by a low- grade B lymphoma (monomorphic proliferation) is observed, sugges- tive of extranodal marginal zone lymphoma (MALT) with an immu- nophenotype: CD20+, CD3-, CD43-, CD5-, BCL6-, CD10-, CD23-, CYCLIN D1- and low proliferative index. In bone marrow there was no infiltration by lymphoma. Currently, after CHOP chemotherapy, he presents a good evolution with complete remission. Conclusion: Primary lymphoma is an infrequent tumour. It usually has a torpid evolution, sometimes fatal with rapid evolution. Histopatho- logical diagnosis is essential to guide the choice of targeted treatment. E-PS-11-022 A comparative study of Ki67 evaluation in mantle cell lymphoma: human vs. artificial intelligence J. García-Gómez*, A. Castillo, P. Osorio, L. Hernández, M. Jimeno, S. Roca, A. Sánchez, J.L. Mate, G. Tapia Melendo *HOSPITAL U. GERMANS TRIAS I PUJOL, Spain Background & objectives: Mantle cell lymphoma (MCL) is an aggressive B cell non-Hodgkin lymphoma. The Ki67 index is a pow- erful prognostic biomarker for this lymphoma subtype. Here, we study the reproducibility in Ki67 evaluation between observers and compare with artificial intelligence (AI) evaluation. Methods: Ki67 percentage was evaluated in 44 MCL cases by four pathologists by “eyeballing” in 5% increments, and using two AI pro- grams (ClinicalViewer-3DHistech & QuPath). The same selected areas, avoiding residual germinal centres, proliferating T-cells and hot-spots were analysed in both approaches. A cut-off point of 30% was used to classify high/low proliferation cases. Statistics analysis was performed with R package. Results: The concordance between all four pathologists was excel- lent (ICC=0,91) when Ki67 was studied as a continuous variable. Moreover, the concordance between pathologists and AI programs was high for QuPath (CCC=0,93) but moderate with ClinicalViewer (CCC=0,65). However, the agreement between observers was lower when cases where analysed in a dichotomized way applying the recommended cut-off point of 30% (concordance 77,27%), and higher between observers and AI programs (pathologists vs. QuPath: concordance 88,63%; pathologists vs. CinicalViewer: concordance 84,09%). The discrepant cases between observers were mostly near the cut-off point, thus explaining the low concordance in the dichotomized study, whereas the discrepant cases between pathologists and AI programs where randomly distributed. Conclusion: Our results indicate that there is an excellent agree- ment between pathologists in evaluating Ki67 by “eyeballing” as a continuous variable, and it becomes lower when dichotomized using the 30% cut-off. The correlation between pathologist and AI programs was moderate or high, mainly depending on the program used. Importantly, the evalua- tion requires selection of the area of interest by a pathologist, in order to avoid hot-spots, residual germinal centres or proliferating T-cells. E-PS-11-023 Histiocytic/dendritic cell neoplasms following therapy for haema- tolymphoid tumours - transdifferentiation or sui generis? V.M. Godkhindi*, V. Bhat K, A.M. Venkatagiri, V. Mv, S. Mailankody *Department of Pathology, Kasturba Medical College, Manipal, Mani- pal Academy of Higher Education(MAHE), Manipal, Karnataka, India Background & objectives: A subset of histiocytic/dendritic cell neo- plasms are known to be associated with or follow preceding lymphoma/ leukaemia therapy with similar molecular signatures, thus evincing the transdifferentiation hypothesis; however, they also carry additional novel genetic alterations in the histiocytic/dendritic cell lineage. Methods: A series of 3 cases of secondary clonal histiocytic/dendritic cell neoplasms of varied histomorphology & immunophenotype occurring post- therapy for preceding haematolymphoid neoplasms have been discussed. Results: Case 1:17/male, T-ALL on maintenance therapy, complains of generalised lymphadenopathy. Nodal biopsy revealed atypical his- tiocytes, immunopositive for CD68, CD163, CD4, Ki67 10%. Treated with 2 cycles of CHOP chemotherapy followed by trametinib, suc- cumbed to progressive disease. Case 2:13/male, B-ALL on maintenance therapy, complains of swell- ing over right distal femur. Biopsy revealed Blastic plasmacytoid den- dritic cell neoplasm, immunopositive for CD4, CD56, CD123, BRAFp. V600E, Ki67 60%. 2 cycles of ICE chemotherapy followed by resection and 2 cycles adjuvant chemotherapy. Patient well. Case 3: 48/male, MDS-h, low blasts on therapy, imaging revealed lytic lesion in left proximal tibia. Biopsy revealed high-grade histiocytic sarcoma marking with CD68, CD163, CD4, S100, Ki67 60%. Lost to follow-up. Conclusion: Histiocytic/dendritic cell neoplasms arising in the setting of preceding cytotoxic therapy for haematolymphoid neoplasms are extremely rare. The 5th edition of the WHO classification of tumours of haematolymphoid tumours envisions an enhanced grouping framework with the introduction of a newly segregated category of Secondary myeloid neoplasms; post cytotoxic therapy. Along the same lines, we propose the decoupling of histiocytic/dendritic cell neoplasms arising post-therapy from the general framework of histiocytic/dendritic cell neoplasms into a unique subgroup, thus facilitating focused research. E-PS-11-024 Rare primary extranodal lymphoma of the genitourinary tract in a human immunodeficiency virus positive young woman E. Horvath*, E. Lázár, O. Cotoi, S. Turdean, G. Molnár, J. Köpeczi *Department of Pathology, Faculty of Medicine, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mureş, Romania Background & objectives: Plasmablastic Lymphoma of HIV-positive patients may be the initial manifestation or a complication of immuno- deficiency with an aggressive clinical course. Typically presents as a mass in the oral cavity and/or gastro-intestinal tract, but >1% of PBL cases include other localizations. Methods: Because lymphomas with plasmablastic differentiation may lead to diagnostic dilemmas, we reported a PBL of genitourinary tract, which show all the characteristic features helping establishment of the diagnosis. A 25-year-old woman, without relevant previous anamnesis presented in emergency service with acute urinary retention. MRI and ultrasound examination revealed tumoral involvement of the bladder, vagina, uterus and bilateral adnexa. Results: Histopathological examination of solid fragments obtained by transurethral resection showed large areas of coagulative necrosis, rich in apoptotic nuclear debris and nests of tumour cells with frequent mitotic figures and tingible body macrophages, resulting in a ‘starry-sky’ appearance. Detailed immunophenotypic analysis confirmed the origin of terminally differentiated plasma cells, which were CD138, MUM1, and kappa chain positive. B cell markers such as CD20 and PAX5 were not expressed. As immunophenotypic aberrances, CD10 and CD56 were also detected. HIV immunodeficiency was confirmed by immune serol- ogy and viral load analysis. Based on primary pelvic localization, after high-dose chemotherapy bilateral adnexectomy was performed. The his- tological examination of ovaries resulted in the same diagnosis. Conclusion: Because patients with HIV-associated PBL have been reported to respond better to chemotherapy compared to HIV negative PBL subjects, identification of HIV infection is important the in those diagnosed de novo with PBL.