ECP 2023 Abstracts

S48 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 cells and multinucleated giant cells with pleomorphic nuclei; viii) S100 protein immunoreactivity. Regardless of the histopathological findings and risk stratification mod- els, all tumours showed a benign clinical behaviour. Conclusion: Although the pathological diagnosis of SFT is usually straight- forward, some difficulties may occasionally arise mainly due to the wide morphologic spectrum exhibited by this tumour. The key histological features for a correct diagnosis of SFT are: (i) tumour circumscription; (ii) bland-looking spindle-to ovoid-shaped cells; (iii) “patternless” growth pattern (haphazard arrangement of neoplastic cells); (iv) alternating hyper- cellular and hypocellular areas; (v) prominent vasculature with hemangio- pericytoma-like pattern and/or perivascular hyalinization; (vi) thin to thick collagen fibres; (vii) low mitotic index (<3/10 HPF). OFP-12-009 Comparative study of diagnostic tools for the detection of MDM2 amplification: fluorescent in situ hybridization, immunohistochem- istry, MLPA and massive sequencing C.M. Ortega Albiach*, J. González, P. Masia Minguez, A. Ferrandez Izquierdo, S. Navarro Fos, C. Martinez Ciarpaglini *INCLIVA, Spain Background & objectives: MDM2 targets the tumour suppressor gene p53. Although MDM2 amplification is useful for the diagnosis of lipomatous tumours, there is no clear evidence on how the results of different methods for the study of MDM2 copy-number are correlated. Methods: We assessed the state of M2M2 amplification through NGS (Oncomine Childhood panel, Thermofisher), IHC (MDM2 clone 1B10, Gennova), FISH (ON MDM2 (12q15) / SE 12, Leica Biosystems) and MLPA (SALSA MLPA Probemix P105 Glioma-2, MRC Holland) in a retrospective series of mesenchymal tumours diagnosed in our institution. Results: We evaluated 98 cases. We built two cohorts of amplified (10%) and non-amplified cases (57%) in which the results of FISH and NGS were concordant. Amplified cases showed MLPA ratio ≥ 3, IHC expression in ≥ 70% tumour cells with moderate to strong staining intensity, and HScore ≥ 140. Non-amplified cases had: MLPA ratio < 2, IHC expression in ≤ 20% of cells with weak to moderate intensity and HScore ≤ 60. Based on this results for MLPA and IHC, we analysed the cases where FISH and NGS were initially discordant, to understand better the rea- sons and potential pitfalls to be considered in clinical routine practice. Conclusion: The IHC study of MDM2 is a cost-effective subrogate marker for the prediction of amplification if adequate cut-off points are established. In cases with intermediate degrees of staining, it is desirable to use a molecular technique to discern the state of the gene. NGS and MLPA show excellent agreement with FISH, however, cases with low levels of amplification or samples with low concentration of tumour cells, may show false negative results. OFP-12-010 Characteristics of pulmonary artery wall remodeling in patients who died of COVID-19 S. Nikolaienko*, S. Gychka, T. Amalyan, V. Vasylyk, M.S.A. Tuffaha, Y. Suzuki *Bogomolets National Medical, Ukraine Background & objectives: Lung damage and the development of res- piratory failure are the major cause of death in COVID-19. The aim of this research is to characterize lung arterial smooth muscle cells in the course of COVID-19. Methods: 22 lung tissue samples from patients died of COVID-19 were divided in two groups (group 1 – death up to 7th day, group 2 – on 14-16 day) and studied with light microscopy, Masson’s trichrome stain, immunohistochemistry (alpha-smooth muscle actin). Morphome- try included arterial wall thickness, AWT, (ImageJ software). Statistical analysis included descriptive statistics and Mann–Whitney test (SPSS Statistics v. 28). Results: In group 1, lung changes included signs of ARDS. Thicken- ing of the lung arterial walls was caused mainly due to the edema and initial fibrosis as well as angiomatosis of the adventitia. In group 2, thickening of the arterial walls was related to the media and com- bined with pronounced fibrosis of the adventitia and perivascular areas. Results for group 1: AWT Average=8,19 μm (SD=2,23 μm), in group 2: AWT Average=16,49 μm (SD=4,26 μm). Mann–Whitney U test showed statistically significant difference in distribution of AWT between groups (p<0,001). Conclusion: Severe course of COVID-19 is associated with the thick- ening of pulmonary arterial walls due to the proliferation of smooth muscle cells as well as the development of fibrosis in the adventitia. The development of remodelling is a characteristic of a longer course of the disease. This factor should be taken into account in the reha- bilitation of COVID-19 convalescents who have had a long course of disease. Funding: Funded by NIH (R03AG71596) OFP-12-011 Dynamics of SARS-CoV-2 spike protein and nucleocapsid protein in lung tissue of patients died of COVID-19 S. Gychka*, S. Nikolaienko, T. Amalyan, V. Vasylyk, M.S.A. Tuffaha, Y. Suzuki *Bogomolets National Medical University, Ukraine Background & objectives: SARS-CoV-2 infection causes lung dam- age with the development of acute respiratory distress syndrome (ARDS), pneumonia, pneumofibrosis, and respiratory failure. Rate of elimination of the virus from the lung tissue is one of the factors affect- ing the degree of lung damage. Methods: 22 lung tissue samples form patients died of COVID-19 were divided in two groups (group 1 – death up to 7th day, group 2 – on 14-16 day) and studied with light microscopy, immunohistochemistry (spike gly- coprotein, SG; nucleocapsid protein, NP). Expression levels were scored as 0-3; for SG both in intima, SGI, and media, SGM; NP only in intima. Results: Morphological changes of the lungs during the severe course of COVID-19 transformed mainly fromARDS in group 1 to secondary bacte- rial pneumonia and pneumofibrosis with remodelling of the arterial walls in group 2. Statistical analysis included descriptive statistics and Mann– Whitney U test (IBM SPSS Statistics v. 28). Results for group 1: SGI AV=1,5 (SD=0,53), SGM AV=0,7 (SD=0,48), NP AV=1,2 (SD=0,42). For group 2: SGI AV=0,64 (SD=0,39), SGM AV=0,64 (SD=0,32), NP AV=0,91 (SD=0,63). Mann-Whitney U test showed statistically significant difference in distribution of SGI between groups (p=0,002). No difference in SGM and NP between groups were found. Conclusion: A decrease in the expression of spike glycoprotein in the intima of the pulmonary arteries was detected in patients who died on the 14th-16th day of the course of the disease. The low expression of spike glycoprotein during the third week of the disease indicates the leading role of secondary complications in the cause of mortality. Funding: Funded by NIH (R03AG71596) OFP-12-012 Primary Ewing sarcoma/Primitive neuroectodermal tumour of the kidney: Experience from a rural teaching hospital in South India V.M. Godkhindi*, R. Kudva, K. Pai, S. Sharma, M. Mathew, G. V, A. C K Rao, V. Monappa, S. P S, B. Nayal, D. Nayak M, B.M.K. Singh, C.B. K Udupa, D. H C *Department of Pathology, Kasturba Medical College, Manipal, Mani- pal Academy of Higher Education (MAHE), Karnataka, India Background & objectives: Primary renal Ewing sarcoma is a rare subset and often requires a multimodal approach synergising between