ECP 2023 Abstracts

S387 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 PSAP expression was able to predict PSA recurrence independent of pre- and postoperative prognostic markers in ERG negative cancers. In extra-prostatic cancers, PSAP immunostaining was only seen in 3 of 94 (3.2%) neuroendocrine tumours of the pancreas and in 1 of 129 (0.8%) diffuse type gastric adenocarcinomas. Conclusion: A positive PSAP immunostaining is highly specific for prostate cancer and reduced PSAP expression is associated with an aggressive prostate cancer phenotype. The independent association of reduced PSAP expression with poor prognosis in ERG negative pros- tate cancer makes PSAP measurement a candidate marker for prognos- tic multiparameter panels for prostate cancer. E-PS-24-080 Tuberous sclerosis - associated chromophobe renal cell carcinoma – a rare case report of a family C. Valavanis*, E. Souka, N. Skouteris, G. Papageorgiou, N. Charalam- pakis, G. Stanc *Molecular Pathology Unit Metaxa Cancer Hospital, Greece Background & objectives: Tuberous sclerosis complex (TSC) is a genetic disorder characterized by intellectual disability, epilepsy, facial angiofibromas and tumour formation in multiple organs, including the kidney. Renal cell carcinoma occurs in 2%–4% of patients with TSC. Methods: A case of two sisters, 38-year-old and 36-year-old, respec- tively, diagnosed with eosinophilic chromophobe renal cell carcinoma, in a randomized control with no systemic manifestations. Both sisters and mother had c.170G>A/p.(Arg57His) mutation in the TSC2 gene in heterozygocity. The father has no TSC2 mutations. On gross examination both tumours were brown, well circumscribed and solid, measuring 6,5X5X4cm and 8,5X6X5,5cm in dimensions. Results: Microscopic examination revealed neoplastic cell population of medium sized cells with eosinophilic cytoplasm (> 80% of the cells), perinuclear halo, round nuclei with small rare conspicuous nucleoli. In some areas the nuclei have irregular nuclear membrane, folded or raisinoid. No mitotic figures or necrosis were recognized. Immunochemistry displayed positivity for CK7, CK8/18, E-cadherin, EMA and CD117. Negative were Vimentin, RCC, CAIX, CD10, HMB45, Melan A, AMACR and PAX-8. In our case the mutation TSC2 gene in heterozygosity was currently considered to be VUS. The diagnosis of Chromophobe Renal Cell Carcinoma of eosinophilic variant was made. Conclusion: The TSC-associated renal cell carcinoma has been recog- nized for many decades. Based on the bibliography (case series) they tend to occur more often in young females, are multiple or bilateral, with indolent course. Metastases have been reported. Hybrid Oncocytic / Chromophobe Renal Cell Carcinoma are com- monly described in patients with Birt-Hogg Dubé syndrome. E-PS-24-081 Evaluation of the rates of histological subtypes of urothelial carci- noma (UC) and divergent differentiation on trans-urethral tesec- tion of bladder tumour (TURBT) specimens C. Ward*, N. Swan *Saint Vincent’s University Hospital, Dublin, Ireland Background & objectives: The updated WHO Classification of Tumours highlights the prognostic significance of histological subtypes and divergent differentiation of UC. Identification may alter clinical management significantly, while it is suggested they are under-reported. We aimed to assess rates in a tertiary hospital. Methods: We reviewed histopathology reports of all malignant TURBT cases over a one-year period (August 2020-August 2021). Patients with confirmed UC were included and the rates/types of diver- gent differentiation and/or histological subtypes were recorded. Clin- icopathological data regarding grade (WHO 1973 and WHO 2004), detrusor involvement, stage, carcinoma in situ were also recorded and assessed for report completeness as per RCPath recommendations. Results: We identified 131 malignant cases on TURBT specimens over the study period. Cases of pure squamous cell carcinoma (2/131) and adenocarcinoma (1/131) without a urothelial component were excluded. Of 128 UCs there were eight cases of divergent differentia- tion (6.25%) comprised of squamous cell carcinoma (5/8) and small cell carcinoma (3/8). Four histological subtypes were identified (3.13%) including clear cell (2/4), lymphoepithelioma-like (1/4) and micropap- illary (1/4). Report completeness was 84.4% with carcinoma in situ the predominant omitted factor (18/128). Conclusion: Histological subtypes and divergent differentiation in UC are diverse and often subtle. Recognition is crucial given significant implications for treatment and prognostication as outlined in the recent WHO 5th edition. Rates are reported to range from 16-25%, however there is marked heterogeneity across studies. We report rates of 9.38%, suggesting that they are under-reported. Important clinicopathologi- cal factors were omitted in 15.6% of reports. These findings highlight the increasing complexity of subspecialties in histopathology and the potential role for standardized reporting. E-PS-24-084 Metanephric adenofibroma: case report V. Zakharava*, P. Kisialeu *N.N.Alexandrov National Cancer Centre of Belarus, Belarus Background & objectives: Metanephric adenofibroma (MAF) is a rare tumour with a favourable prognosis from metanephric tumour fam- ily wich may include the morphologic features between benign pure metanephric stromal tumour and pure metanephric adenoma. Objective was to study the immunomorphological features of MAF. Methods: Morphological examination and immunohistochemistry of MAF was performed: CK7, WT1, CD57, Desmin, S100, SMA, CD34, Inhibinα, ER, PR, Ki67. An 18-year-old man presented with a 30*17*27 mm solitary tumour of a lower pole of the left kidney with heterogeneous structure and multiple calcifications, irregular contour extending beyond the renal capsule. Subsequently, laparoscopic resec- tion of the kidney was performed. Results: Histologically, this was a well-defined tumour with focally irregular margin. The stromal component was prevalent ( ˃ 85%) and was composed from fibrous bland spindle and stellate cell tissue with vari- able size of tubules (small to cystic, CK7+, CD57+/-, WT1-, CD10+/-, Inhibinα-) and a perifocal inflammatory response. The mesenchymal component showed immunoreactivity for CD34 and PR and was nega- tive for SMA, Desmin, Inhibinα, ER, and Ki67 (~1%). The epithelial component was composed of primitive tubules with bland cytology and multiple psammoma bodies. The adenomatous component showed nuclear positivity for WT1 (~90% tubular cells) and PR, cytoplasmic/ membrane expression of CD57 and focally CK7, negative staining for CD10, Inhibinα, ER, no mitotic activity (Ki67˂1%). Conclusion: We report the case of metanephric adenofibroma of the kidney in 18-year-old man, histologically and immunohistochemically presented as a biphasic tumour with a predominance of metanephric stromal tumour component (CD34+ and PR+) and a focal component identical to metanephric adenoma (WT1+, CD57+, focally CK7+ and PR+). Intratumoral angiodysplasia and concentric cuffing of entrapped