ECP 2023 Abstracts

S385 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 Results: We received a partial nephrectomy specimen almost totally occupied by a tumour measuring 2,5 cm in greatest dimension, well delineated from the adjacent parenchyma, with a solid and brown cut sur- face. Histologic examination showed a well delineated, non-capsulated neoplasia composed of small to intermediate size vessels surrounded by a concentric proliferation of spindle to ovaloid cells with eosinophilic cytoplasm, elongated to ovaloid regular nuclei without nucleoli. The intervening stroma was oedematous or collagenous. There were no areas of necrosis or atypical mitotic figures. Immunohistochemistry revealed expression of SMA, Collagen type IV, Bcl-2 and CD34 (focal and weak) in the neoplastic cells with negativity for Desmin, HMB-45, Melan-A and STAT6. Conclusion: Myopericytomas are characterized by a perivascular con- centrical proliferation of spindle or ovaloid cells. Typically, these cells express SMA and h-caldesmon and, more rarely, CD34 and desmin on immunohistochemical staining. Some studies also report positivity for Collagen type IV and Bcl2. Tumours located in the kidney tend to be larger than peripheral tumours (5.6cm vs < 2cm). The prognosis of these lesions is excellent with no cases of recurrences or metastasis with the longest follow-up time being 66 months. E-PS-24-072 A rare subtype of urothelial carcinoma: lymphepithelioma-like carcinoma D. Sá*, S. Neves, F.S. Vieira, A. Duarte, F.E. Costa, J.R. Vizcaíno *Centro Hospitalar Universitário de Santo António, Portugal Background & objectives: In the urinary tract, lymphoepithelioma- like carcinoma (LELC) typically arises in the urinary bladder. It was first reported by Zuckerberg et al in 1991, and it is uncommon with a reported incidence between 0.4 and 1.3% of all bladder carcinomas. Methods: We herein report a case of an 83-year-old man that went to the emergency department with a three-day history of haematuria. He was submitted to a bladder ultrasound which revealed a 3cm polypoid lesion on the anterior wall. Urinary cytology was suspicious for high grade urothelial carcinoma. The patient was then submitted to a tran- surethral resection of the lesion. Results: We received a transurethral resection specimen that weighted 1g and was composed of six fragments. Histologic examination showed fragments of bladder wall infiltrated by a neoplasia characterized by sheets of cells with eosinophilic cytoplasm and round nuclei with prominent eosinophilic nucleoli admixed on an inflammatory back- ground, imparting a syncytial appearance. The tumour was confined to the lamina propria of the mucosa, not invading the muscularis propria. Immunohistochemistry revealed expression of CKAE1/AE3, CK7, p63 and GATA3 in the epithelial cells and CD45 in the inflammatory cells. Chromogenic in situ hybridization (CISH) for the detection of Epstein- Barr virus-encoded RNA (EBER) was negative. Conclusion: Amin et al. proposed the division of these tumours based on the percentage of LELC pattern with pure, predominant, and mixed types composed of, respectively, 100%, ≥ 50% and < 50% of the tumour with LELC pattern. Some authors report a more favourable prognosis and better response to systemic chemotherapy when pure or predominant. Others have found no differences between LELC and conventional urothelial carcinoma. CISH-EBER has been reported to be consistently negative in different series in these tumours. E-PS-24-073 Intertubular growth of testicular seminoma; a distinct clinical and pathological entity E. Salmo* *Royal Oldham Hospital, United Kingdom Background & objectives: Intertubular growth of seminoma is a rare entity but present a distinct subset of such tumours. It does not usually present or detected as a mass and may be discovered during work-up for testicular related problems. Methods: No distinct tumour is grossly apparent in most of these cases. Microscopic examination usually shows the tumour cells to infiltrate between the seminiferous tubules forming no solid lesion. Evidence suggests that this type of seminomas represent a more aggressive semi- noma variant. Results: A 42-year-old man presented with a testicular lesion and clinically suspected to have left testicular cancer. A testis weighing 36.2 grams received at the pathology laboratory showing vague yellow nodule measuring 10mm in diameter which appeared to be limited to the testis. Microscopy showed a diffuse tumour composed of thin trabeculae and cords of tumour cells showing the typical H&E appearance of a seminoma. The tumour cells were positive for OCT3/4, CD117 and PLAP. There microscopic tumour size measured 20mm in maximum diameter, greater than the documented macroscopic size of 10mm due to the diffuse nature of most of the tumour. The tumour staged as pT1. Conclusion: A diagnosis of seminoma with intertubular growth was entertained. Seminomas may present exclusively with intertubular growth with altered echogenicity seen on ultrasound examination in such cases and may feel firm at palpation. It is important to identify this sub-type of sem- inomas as such tumour appeared to be associated with worse prognosis that the typical pattern of seminomas. In addition, this sub-type of semi- nomas are associated with prominent lymphocytic infiltrate admixed with the tumour cells making their identification difficult and challenging. E-PS-24-074 Prognostic significance of inactivated Forkhead Box O1 (FOXO1) in non-muscle-invasive bladder cancer M.M. Savas*, F. Gürsoy, F.Y. Suçeken, I.E. Zemheri *SBÜ Ümraniye EA Hastanesi, Turkey Background & objectives: FOXO1, a transcription factor, promote apoptosis which is known as a tumour suppressor in several types of malignancies including bladder cancer. The present study aimed to determine the alteration of expression of pFOXO1 in patients with bladder cancer. Methods: 112 consecutive patients who underwent at least two recur- rent bladder biopsies in our hospital between 2008 and 2022 were included. The first and the last biopsies of the patients who had recur- rence and progression were evaluated in terms of change in pFOXO1 staining, clinicopathological features and prognosis. The Immunore- activity scoring system (IRS) was used to evaluate nuclear pFOXO1 staining. Results: At a median follow-up of 43 months, 49 (43.7%) of the 112 patients had shown tumour progression while 63 (56.3%) of those had not. When comparing the last biopsy with the first biopsy, decreased pFOXO1 nuclear staining was associated with progression while increased pFOXO1 nuclear staining was not (p=0.039). On the other hand, in 28 patients (25%) histologic grade was found to be increased, unchanged in 70 of those (62.5%) while decreased in 14 (12.5%). In terms of the last biopsies, significant associations were found between pFOXO1 positivity and pT stage (P<0.001); histologic grade (p=0,023); lenfovascular invasion (p=0,001); lymph node-positivity (p=0,002) and distant metastasis (p=0,002). Conclusion: Multivariate Cox model showed that pFOXO1 lowness was an independent predictor for prognosis (β=-1,493, P=0.002). In conclusion, staining of pFOXO1 was significantly decreased with higher histological grade, advanced clinical stage and lymph node metastasis in patients with bladder cancer. Thus, pFOXO1 staining may serve as a new prognostic marker for bladder cancer. Funding: Health Sciences University Umraniye Education and Train- ing Hospital