ECP 2023 Abstracts

S369 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 Our purpose is to study the frequency of HER2 overexpression in UCB and its correlation with histo- prognosis parameters. Methods: We performed a cross-sectional and analytic study, enroll- ing all patients diagnosed with UCB on surgical specimen during two years. Immunohistochemistry (IHC) expression was tested by an HER2 antibody and scored according to Hoffman score. In situ hybridization technique (CISH) was performed for cases with IHC2+ score. HER2 overexpression was defined by a score IHC3+ or a score IHC2+ and CISH+. Results: We enrolled in this study 60 patients, with a median age of 67.5 years. A masculine predominance was observed. Patients were divided to four groups according to their HER2 status: 80% were scored IHC 0, 8% were scored IHC1+, 12% were scored IHC3+ and only one case was scored IHC2+.The result of CISH for the case of IHC2+ was negative. Therefore, the HER2 overexpression was observed in 12% of all cases. In our study we didn’t founf any association between HER2 overexpression and bad prognosis parameters: the grade, the tumour staging, vascular and neural invasion, tumour Budding. Conclusion: There is no guidelines for HER2 testing in UCB. In consequence the prevalence of HER2 expression in UC is not well defined. It depends on preanalytical conditions, IHC techniques and the score employed. In concordance with our results, HER2+ prevalence ranged from 6.7% to 37.5% with a weighted average of 13%. Unlike our results, studies found an association between Her2 overexpression with the grade and stage of local infiltration (pT). Studies on a larger scale are needed to verify our results. E-PS-24-010 A case of xanthogranulomatous pyelonephritis mimicking renal neoplasia with clinical and histopathological features H. Berber*, D. Enneli *Ankara University Medical School, Pathology Department, Turkey Background & objectives: Xanthogranulomatous pyelonephri- tis (XGP) is a rare, severe form of chronic pyelonephritis, usually associated with infection and nephrolithiasis. Herein, we present a case of XGP, strongly mimicked renal malignancy with its clinical, radiological, histopathological features, to draw attention to this diagnostic trap. Methods: A 56-year-old female patient was taken into evaluation due to fever and elevated serum acute phase reactants. Bacterial growth (E.coli, E.faecium) was detected in the urine culture. Computerized tomography revealed a mass lesion(8x7cm), in the upper-pole of the left kidney, extending to the perirenal adipose tissue. The patient under- went left radical nephrectomy with a preliminary radiological diagnosis of renal cell carcinoma. Results: Gross examination of the nephrectomy specimen revealed an irregularly circumscribed nodular mass, infiltrating perirenal adipose tissue. It was 5.5 cm in long diameter and had yellow- white cut surface with centrally necrotic, haemorrhagic areas. Microscopically, the renal parenchyma was infiltrated by intense granulomatous inflammation, composed of neutrophils, plasma cells, lymphocytes, xanthomatous histiocytes and multinucleated giant cells. The lesion extended into perirenal adipose tissue. These xanthomatous cells had foamy cytoplasm, mimicking clear cells of renal cell carcinoma. Conclusion: XGP is a rare and agressive form of pyelonephritis, that can be usually confused with renal neoplasias, clinically, radiologi- cally and even macroscopically. As correct preoperative diagnosis is frequently not possible, patients with XGP usually undergo radical nephrectomy and the accurate diagnosis could frequently be made after the histopathological examination of nephrectomy specimen. Patholo- gists should be aware of this entity which can be a good mimicker of renal neoplasia and consider it in the differential diagnosis of renal masses. E-PS-24-011 Cancer prevalence, grade and number of transurethral resections of prostate specimens 2006-2020 M. Bonert*, N. Nikzad, P. Major, B. Shayegan, I. El-Shinnawy *McMaster University / St. Joseph’s Healthcare Hamilton, Canada Background & objectives: Changes in serum PSA screening resulted in a decrease of prostate biopsies, negative biopsies and grade group 1 cancers. However, trends in cancer and grade in transurethral resections of prostate specimens (TURPs) have not been well studied. Methods: All in house TURPs at two centres within a regional labora- tory accessioned 2006-2020 were retrieved. The diagnosis and cancer grade (if applicable) were extracted by a validated hierarchical free text string matching algorithm (HFTSMA). Results: The cohort had 3,790 TURPs. 522 had prostate cancer and of these 27 could not be graded. To assess the HFTSMA, randomly selected specimens were reviewed (200 correct/200) and results were compared to cancer synoptic data (230 correct/232); these confirmed a classification error rate of <1%. Volume varied from 134 to 338 speci- mens/year. A local volume minimum was seen in 2012 and a relative volume decrease in 2020. The number of specimens with low-grade (grade group (GG) 1/2) cancer (270 cases, range: 9 to 35 cases/year) tracked the number of specimens. High-grade (GG3/4/5) cancers (225 cases, range: 8 to 21 cases/year) increased transiently after the 2012 case volume local minimum. Conclusion: The lower TURP procedure volumes in 2011-2013 likely led to the decreased number of low-grade cancers in 2012 and the relative surplus of high-grade cancers in 2013-2014. The modest 2020 procedure volume decrease is probably explained by the COVID-19 pandemic. The association between the number of TURPs and prostate cancer on TURP may allow inferences about prostate cancer prevalence and behaviour in large cohorts. E-PS-24-012 Large nested urothelial carcinoma: clinicopathological study on 12 transurethral resection materials Y. Cakir*, B. Bambul Sığırcı, E. Hacıhasanoğlu, Y.B. Kök, Y. Sağlıcan, K. Behzatoğlu *Dokuz Eylül University, The Institute of Health Sciences, Department of Molecular Pathology, Turkey Background & objectives: Large nested urothelial carcinoma (LNUC) is a rare variant of urothelial carcinoma revealing inverted growth pat- tern, bland cytological features and generally presenting with muscular invasion. In study presents 12 LNUC cases that cause diagnostic dif- ficulties in transurethral resection (TUR) materials. Methods: Haematoxylin&eosin-stained slides of bladder TUR materi- als submitted to our department in 2017-2023 were re-examined. 12 cases were diagnosed with LNUC. Results: 10 cases were male (83,3%). The mean age was 57,7. The average tumour size was 4,4 cm. Non-invasive urothelial carcinoma component was present in all cases. Five and seven cases were pT1, pT2 respectively. Histopathologically, tumours showed invasion of lamina propria or muscularis propria as large nests with inverted pro- liferation. The tumour cells had bland cytological features and the non- invasive urothelial carcinoma (UC) component almost always showed low grade morphology. Tumour-stroma interface was irregular, and fibrous stromal reaction and/or stromal lymphoid infiltration was pre- sent. Most tumours revealed tumoral budding described as small nests in the stromal interface of medium-large nests. Conclusion: Diagnostic problems can be experienced at LNUC because of their bland features and unclear invasion criteria compared to conventional UC. Tumours with an inverted growth pattern, irregu- larity at the stroma-tumour interface, and budding in TUR materials should be evaluated in detail for invasion.