ECP 2023 Abstracts

S74 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 in multiple cellular functions after SMARCA4 knockdown in an ana- plastic thyroid cancer cell line, ASH-3. DNA microarray was used to uncover biologically coherent gene sets. Immunohistochemical analy- sis was performed to detect the expression level of SMARCA4 in 19 anaplastic thyroid patients. Results: In vitro, SMARCA4 knockdown significantly altered the cell proliferation, migration, invasion, and apoptosis of ASH-3 cells. Silencing of SMARCA4 also markedly amended the sensitivity of cisplatin in ASH-3 cells. Knockdown of SMARCA4 influenced the expression of HOX proteins. Ingenuity pathway analysis suggested that the effect of SMARCA4 is regulated by immunogenic cell death signalling pathway, ferroptosis pathway etc. Abundant giant cells with mitotic figures and pleomorphic spindle cells accompanied by inflam- matory infiltration were present in anaplastic thyroid cancer. Immuno- histochemical results revealed that SMARCA4 is highly expressed in anaplastic thyroid cancer tissues. Positive p53 expression was observed in these tissues while cyclinD1 and p63 were negative. Conclusion: Taken together, these results provide new insights into the biological impacts of SMARCA4 in anaplastic thyroid cancer. Fur- thermore, we provide clues to examine SMARCA4 as an imperative biomarker for predicting anaplastic thyroid cancer. Additional research is underway to ascertain functional regulation of SMARCA4 in ana- plastic thyroid cancer. PS-05 | Poster Session Infectious Diseases Pathology PS-05-001 Histopathological characteristics of lesions suspected of Leishma- niasis: report of a series of patients D. Nunes Oliveira*, J. Carneiro Melo, G. Ferreira Morgantetti, G. Alencar Medeiros, H. Neves Feitosa Filho, V. Queirós Calheiros Campelo Maia, F.R. Oliveira Cavalcante Júnior, J.S. Pereira Fil- gueira, J. Silva Pinheiro Firmino, N. Pinheiro Rodrigues *University of Fortaleza, Brazil Background & objectives: Leishmaniasis is a parasitic disease caused by Leishmania parasites, transmitted through the bites of infected sand- flies. Our aim was to analyse the histopathological findings of biopsies from patients suspected to have leishmaniasis. Methods: This was a retrospective, descriptive study of histopathologi- cal reports of biopsies of patients with suspected leishmaniasis, carried out in a pathology laboratory, in northeastern Brazil, from January 2020 to March 2023. The variables age, sex, histopathological sub- type, clinical picture and what was the conclusion of diagnosis were analysed. Results: 39 histopathological reports (36 skin biopsies, 3 gas- tric) with suspected leishmaniasis with a mean age of 37.4 years and 51.2% men. 84.6% with a single lesion located mainly on the lower limb (53.8%). Lesion types included ulcer (46.1%), pap- ule (28.2%) and nodule (25.6%). The main histopathological changes observed were lymphoplasmacytic inflammatory infiltrate, well-formed epithelioid granuloma (43.7%), malformed granu- loma (56.2%) and focal necrosis (15.3%). Leishmania amastig- otes in 17 biopsies (82.3% in the dermis and 17.6% in the gastric mucosa) and Giemsa was positive in 11 (skin) and 3 (stomach). Granuloma (P = 0.030), ulcer formation (P = 0.036) and Giemsa positive (p = 0.0007) were significantly associated with body load. Conclusion: This study investigated suspected cases of leishmaniasis in 39 patients and found that the disease mainly affects adult men with a sin- gle lesion on the lower limb, characterized by ulcers, papules or nodules. Significant associations were found between organism load and granu- loma ,ulcer formation and giemsa positive.It is important to remember that the immunocompromised are not only more susceptible to infection, but also to disseminated disease, including gastric leishmaniasis. PS-05-002 Clinical and morphological features of acute respiratory distress syndrome in lethal cases of COVID-19 D. Shtyrts*, O. Reshetnikova, A. Ermakov, L. Rudiuk *Immanuel Kant Baltic Federal University, Russia Background & objectives: Acute respiratory distress syndrome(ARDS) is one of the most severe clinical complications of the COVID-19. The aim of this study was to reveal pathomorphological and clinical peculiarities of the fatal outcomes of ARDS in COVID-19 patients of various age groups. Methods: Autopsy examinations were performed in 106 fatal cases of COVID-19. Medical histories and full post-mortem examinations data were analysed with emphasis the morphogenesis of the structural changes in the lung parenchyma in correlation with the patient’s age and the length of stay in the hospital. Gross pictures of the internal organs were examined and their tissue samples studied histologically. Results: Studies revealed that 52% of patients with a fatal outcome of ARDS were over 70 y.o., the minimum number was occupied by the age group 31-50 years (12%) and 36% were included in the 51-70 y.o. group. Lung tissue’s histology showed that intra alveolar edema, forma- tion of hyaline membranes, desquamation of the alveolar epithelium and haemorrhagic syndrome were observed in all corpses, with pro- longed duration (up to 21 days) in older patients. On the 8th day of hos- pital stay, all individuals older than 50 years had proliferative features in the lung tissue. Their combination with exudative changes, were recorded for the longest time (up to 30 days) in elderly individuals. Conclusion: The lungs parenchyma’ morphological features in the fatal outcomes of the COVID-19 infection depend on the age of the patient and the duration of the disease (stay in the hospital). The change of acute exudative processes to proliferative ones in most cases is char- acterized by a long-term combined manifestation of both. The morpho- genesis of damage and repair of the lung parenchyma in COVID-19 with an emphasis on the patient’s age should be investigated in order to develop adequate therapeutic strategies. PS-06 | Poster Session Nephropathology PS-06-001 Peritubular capillaritis in lupus nephritis: frequency and rela- tionship with disease activity B.B. Cengiz*, E. Tekin, M.F. Açıkalın, Ş.B. Yaşar *Eskişehir Osmangazi University, Faculty of Medicine, Department of Pathology, Turkey Background & objectives: Lupus nephritis (LN) is associated with a shorter time to death in systemic lupus erythematosus. The objective of this study was to determine the frequency of peritubular capillaritis (PTC) and its relationship with active and chronic lesions in LN. Methods: The specimens of 57 patients diagnosed with LN were re- evaluated using revised 2018 ISN/RPS classification and the modified NIH scoring system. Peritubular capillary inflammation was evaluated according to the Banff classification and cases with PTC scores of 2 and 3 were defined as positive for PTC. The patients were grouped by high/low activity and chronicity index scores. Results: 45 (78.9%) patients were female and 12 (21.1%) were male, with a mean age of 27.43 years (range 8–71). PTC was captured in 45 (78.9%) patients, with PTC scores of 1, 2 and 3 in 20 (35.08%), 20 (35.08%), and 5 (8.7%) patients, respectively. Higher severity of PTC was detected in cases with elevated serum creatinine levels (p<0.001). The severity of PTC was higher in class 4 patients than in class 3 patients (p=0.005). The rate of detection of PTC score 2-3 was higher in patients with an activity index of 6 and above (p=0,032). However, no significant correlation was found between the chronicity index and PTC.