ECP 2023 Abstracts

S377 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 results obtained in a cohort of testicular germ cell tumours (TGCTs) representative of all histological subtypes. Results: Both specimens showed predominantly teratoma, with focal variably sized cysts, lined by large, eosinophilic, squamoid-appearing cells, with frequent vacuolization, corresponding to CTT. Fibrinoid change was common, and no necrosis, marked pleomorphism or mitotic figures were seen. There were areas of transition between (glandular) mature teratoma and CTT in cystic spaces. Tumours were positive for CK8/18, with multifocal positivity for GATA-3, and positivity for HCG in scattered cells only. Alpha-inhibin, OCT3/4 and p63 were negative. Patients are alive with stable disease at two years of follow-up. MiR- 371a-3p levels in CTT were undetectable, as well as in additional tera- toma cases, while being elevated in seminomas, embryonal carcinomas, yolk sac tumours and choriocarcinomas. Conclusion: Recognition of CTT is important, avoiding the pitfall of diagnosing choriocarcinoma foci, which would dictate a much poorer prognosis and lead to unnecessary systemic treatments. CTT behaves similarly to teratoma. The finding of transitions between mature tera- toma and CTT, as well as the negativity for miR-371a-3p (a universal biomarker of TGCTs, being negative only in teratoma) in CTT support a maturation phenomenon towards teratoma. This is the first report of miR-371a-3p testing in CTT. Funding: The authors would like to acknowledge the support of ‘Bolsa de Investigação Médica LPCC/Lions – Cancro Infantil’ 2022 and PI27 – Financiamento Base GEBC. E-PS-24-042 Fumarate hydratase-deficient renal cell carcinoma, a diagnostic pitfall in the renal tumours classification A. Loghin*, M. Decaussin-Petrucci, C. Chibelean, M.C. Popelea, A. Raicea, A. Borda *G.E. Palade UMFST Targu Mures, Romania Background & objectives: Fumarate hydratase deficient renal cell carcinoma (FH-deficient RCC) is a RCC characterized by variable mor- phologic aspects and germline mutation in the FH gene. Methods: We present the case of a 65 years-old men admitted to the Urology Department, where a left nephrectomy was performed for a of 130 mm renal tumour. The specimen was sent to the Pathology Department. Results: The macroscopy revealed a tumour with solid and cystic architecture, with a fibrous capsule, extended in the perirenal adipous tissue. Microscopically, we observed multiple admixed morphologi- cal patterns: papillary, tubulo-cystic and cribriform. The tumour cells had eosinophilic cytoplasm, large nuclei, focally with eosinophilic macronucleoli. Also, in some cells, intracytoplasmatic vacuoles were present. These findings were not characteristic for any common type of RCC. In immunohistochemistry tumour cells were positive for PAX8, focally for AMACR, negative for CD10, CK7, TFE3, CK20, CD117, with preservation of SDHB expression and loss of FH expression. The morphological aspect and the immnohistochemical profile lead to a diagnostic of a FH-deficient RCC. Conclusion: The recognition of FH-deficient RCC is important because of its very aggressive behaviour and also because of the association with Hereditary Leiomyomatosis and Renal Cell Cancer Syndrome. Therefore FH immunohistochemical expression must be determined in all cases of renal tumours without a classic morphologi- cal aspect and immunohistochemical profile. Funding: FDI internalization of higher education E-PS-24-043 TFE3-rearranged renal cell carcinoma: a case report W. Majdoub*, K. Ben Lazreg, A. Baccouche, A. Bdioui, O. Belkacem, D. Benletaifa, F. Saidani, S. Hmissa *Pathology Department Sahloul Hospital, Tunisia Background & objectives: Transcription factorE3-rearranged renal cell carcinomas (TFE3-RCCs) harbour gene fusions involving TFE3. This RCCs account for 40% of paediatric RCCs and 1.6-4% of adult RCCs. Herein we report another rare case report. Methods: A 15-year-old adolescent presented with right lumbar pain and haematuria. The diagnosis of right renal tumour was made by radiologic examinations. The patient underwent a nephrectomy. Results: At macroscopic examination, the tumour was medio-renal measuring 7x6cm. It was white yellowish with haemorrhagic aspects and infiltrated focally the renal capsule without infiltration of the renal vein. Microscopically, the tumour had heterogenous aspects: papillary and diffuse pattern. Tumoral cells were large epithelioid with clear or focally eosinophilic cytoplasm. Multiples psammomatous bodies were observed. There was no rhabdoid or sarcomatous component. On immunohistochemistry stains, tumoral cells were diffusely positive for CD10 and AMACR and focally positive for HMB45 and EMA. Immunostains for Vimentin, ck7 and MelanA were negative. Strong and diffuse nuclear staining for TFE3 was observed. Conclusion: TFE3-RCCs have heterogeneous morphological and immu- nohistochemical profile. Cases presenting at a younger age or cases with atypical morphology are suspected to be a TFE3-RCC.TFE3 IHC anti- body have a high predictive value for detecting TFE3 rearrangement. Paediatric patients with TFE-RCCS have a better prognosis than adults. E-PS-24-044 Clinical and morphological characteristics of bladder cancer A. Malysheva*, O. Reshetnikova, O. Teleshova, O. Zinchenko, M. Malich, I. Sinenko *Immanuel Kant Baltic Federal University, Russia Background & objectives: Bladder cancer (BC) is a severe disabling disease that requires careful differential diagnosis. The aim of the pre- sent study was a statistical analysis of the prevalence of bladder cancer, assessment of its histological variants and stages of the process. Methods: The study was conducted in the Department of Pathol- ogy, Luhansk Regional Oncology Center. A total of 307 cases with suspected bladder tumours were analysed. The results of histological examinations of the tumour, as well as the frequency of various cancer types in different age group of patients were considered. Results: The bladder tissue samples were obtained during the transure- thral resection of the tumour in 79.1% of cases and in 20.9% of cases a diagnostic biopsy was performed. Patients were divided into several age groups: up to 55 years (61 cases), 55-64 years (107 cases), 65-74 years (109 cases) and over 75 years (30 cases). BC was more common in men (82.4%) than in women (17.6%). The highest incidence rate was in the 65-74 y.o. age group (35.5%). Moderately differentiated urothelial carcinoma was a leading histological variant of the BC. The predominant BC stage at the time of the pathology diagnostics was a T1 with the invasion into the submucosal layer. Conclusion: BC is associated with an important health care problem due to the morbidity and mortality associated with disease. The challenge is to control neoplasia based on pathomorphology and morphogenesis of the tumour growth. Based on the data obtained, the need for further com- prehensive clinical and morphological studies is discussed, taking into account information about BC histopathology, socioeconomic factors, detailed information the treatment, its side effects and causes of death. E-PS-24-045 Sarcomatoid chromophobe renal cell carcinoma: a case report S.J. Marín Asensio*, A. Cuesta Díaz de Rada, O. García-Galvis, M.G. Rodríguez Guevara, J. Alzoghby-Abi-Chaker, C.J. Martinez Martinez, A.R. Gonzalez Medina, A. Farres Rabanal, F. Izquierdo García *Complejo Asistencial Universitario de León, Spain Background & objectives: Chromophobe renal cell carcinoma (CRCC) is the third most common type of renal cell carcicnoma (RCC)