ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 pleomorphism and brisk bizarre multipolar mitotic activity. Some areas revealed an epithelioid morpholgy. The tumour infiltrates massively the prostatic gland. Immunohistochemistery showed positive staining for vimentine and smooth muscle actine. Tumour cells were negative for Cytokeratin and CD34.Subsequently, the diagnosis of high grade leiomyosar- coma was made. Meanwhile, the patient had died. Conclusion: Primary prostatic leiomyosarcoma is a rare aggres- sive neoplasm with misleading clinical features which may delay the diagnosis. Generally, the overall prognosis is poor. There are no guidelines concerning the therapeutic approach since primary prostatic sarcomas are extremely uncommon. E-PS-24-048 Fumarate hydratase deficient renal cell carcinoma – a case of hereditary leiomyomatosis and renal cell carcinoma - associated renal cell carcinoma? D. Sá*, F. Costa, F.S. Vieira, J.R. Vizcaíno *Centro Hospitalar Universitário do Porto, Portugal Background & objectives: Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is an inheritable autosomal dominant syndrome caused by germline mutations in the fumarate hydratase (FH) gene and is characterized by the development of cutaneous and uterine leiomyo- mas and renal cell carcinoma (RCC). Methods: We report a case of a 56-year-old man with a renal lesion measuring 10 cm associated with lymph node metastasis and peritoneal carcinomatosis, found incidentally on a CT scan in 2014. After 5 years of chemotherapy, a pancreatic lesion measuring 5 cm was also found on a follow-up CT scan. The patient was submitted to a total nephrectomy and splenopancreatectomy. Results: We received a total nephrectomy specimen with a solid capsulated neoplasia on the upper pole of the kidney measuring 4,5 cm with a white and firm cut surface that invaded the ipsilat- eral adrenal gland. The splenopancreatectomy specimen showed a similar appearing neoplasia involving the pancreas, peripancreatic fat and lymph nodes. At histologic examination the neoplasia pre- sented papillary, tubular, and solid architecture, cells with clari- fied or eosinophilic cytoplasm, prominent nucleoli (grade 3 WHO/ ISUP) and perinucleolar halo. Immunohistochemistry revealed multifocal positivity for CAIX, AMACR, CK34βE12, CD10 and Vimentin in the neoplastic cells with negativity for CK7 and TFE3. There was loss of expression of Fumarate Hydratase. Conclusion: Our patient had no history of cutaneous leiomyomas. As the germline mutation status is often unknown at the time of diagnosis, and not all cases are syndromic, the term FH-deficient RCC is preferred over HLRCC-associated RCC. FH-deficient RCCs demonstrate a variety of architectural patterns and therefore a low threshold for immunohistochemistry is recommended in difficult cases. The estimated lifetime renal cancer risk for FH mutation carriers is estimated to be 15-30%. Our patient is alive 9 months after the surgery. E-PS-24-049 A recently described entity: biphasic squamoid alveolar papil- lary renal cell carcinoma D. Sá*, J.R. Vizcaíno, F.S. Vieira *Centro Hospitalar Universitário do Porto, Portugal Background & objectives: Biphasic squamoid alveolar papillary renal cell carcinoma (BSA-PRCC) was first described in 2012 by Petersson et al. who reported two cases of tumours with a distinctly dual-cell population composed of alveolated islands of large squamoid cells sur- rounded by smaller cells. Methods: We herein report a case of a 61-year-old woman who was submitted to a renal ultrasound due to a six-month history of sustained weight loss. The ultrasound and subsequent CT scan revealed a renal mass in the lower pole of the kidney measuring 1,5 cm. To remove this lesion, a partial nephrectomy was performed. Results: We received a partial nephrectomy specimen almost totally occupied by a tumour measuring 1,8 cm with a solid and yellow-tan cut surface. Histologic examination showed a distinctly dual cell population, one of relatively uniform, small neoplastic cells with clarified cytoplasm and round low-grade nuclei form- ing alveolar-like structures. The other, separated from the former by a slit space, composed of solid nests of larger squamoid cells with eosinophilic voluminous cytoplasm and large nuclei with prominent nucleoli (grade 2 WHO/ISUP). Immunohistochemistry revealed expression of CK7, AMACR, EMA, CK34βE12, CD10 (focal) and Vimentin (focal) in the neoplastic cell with negativity for CAIX. Cyclin D1 highlighted the squamoid cell islands. Conclusion: Biphasic squamoid alveolar papillary renal cell carcinoma has been mainly described as a morphological variant of renal cell carcinoma (RCC). Its incidence has been estimated at less than 1% of papillary RCC. MET alterations and chromosome 7 trisomy have been recently reported in, respectively, 60% and 87,5% of BSA-PRCCs linking it to type 1 papillary RCC. Metastases occur in 9,4% of the cases but fortunately our patient is currently free of disease 13 months after the surgery. E-PS-24-050 An unexpected presentation of renal cell carcinoma as a renal hilar lymph node metastasis without radiologically or macroscopically evident renal mass E. Gedik*, E. Dicle Serbes, İ. Adanır, C. Cansız Ersoz, E. Süer, G. Kaygusuz, D. Enneli *Ankara University Medical School Pathology Department, Turkey Background & objectives: It’s extremely rare for renal cell carcinoma(RCC) to be diagnosed from metastasis without evidence of radiologically/macroscopically renal mass. The present case was diagnosed from lymph node metastasis, as there wasn’t any renal mass. It was striking with many other features. Methods: A 73-year-old woman was admitted to the hospi- tal with abdominal pain. CT, PET/CT scans revealed a well- demarcated mass between the left kidney hilum and aorta (SUV- max=30.6), with a radiological appearance of lymphadenopathy. Fine-needle aspiration biopsy from the mass revealed a poorly differentiated, malignant epithelioid tumour with a preliminary diagnosis of sarcoma, due to epithelial-marker negativity. Patient underwent left radical nephrectomy. Results: Macroscopically, a solid hilar mass, 9,5cm in long diam- eter, unrelated to the renal parenchyma/pelvicalyceal system was detected. No renal mass was noticed. Microscopically, tumour cells effacing the lymph node parenchyma were arranged in solid and alveolar pattern. They were polygonal with vesicular nuclei, promi- nent eosinophilic nucleoli, abundant eosinophilic cytoplasm, some with rhabdoid differentiation. Extensive necrosis was noted. Immu- nohistochemically, Pancytokeratin, EMA, PAX-8,Vimentin,RCCag, CD10, were positive, suggesting that the tumour was RCC metas- tasis. Based on these immunohistochemical findings, renal paren- chyma was totally resampled, two distinct microscopic RCC foci (Low grade clear RCC-4mm, Chromophobe RCC-2mm) were S362