ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 These findings were consistent with the diagnosis of low grade non-invasive papillary urothelial carcinoma. Rare lamellated or coarse-fibred bone trabeculae separated by loose fibrous connec- tive tissue with osteoid seams were found in the tumour stroma. Numerous cells with blue cytoplasm that correspond to osteo- blasts outlined those osteoid and bony structures, without atypia or pleomorphic stromal cells. Conclusion: Stromal osseous metaplasia is a rare benign condi- tion found in urothelial carcinomas. Its presence has no effect on their therapeutic approach, which is determined by histologic grade and tumour stage. Metaplastic bone, on the other hand, must be distinguished from malignant osteogenous conditions, most notably sarcomatoid carcinoma. E-PS-24-019 Histoepidemiological study of eosinophilic metaplasia of the prostate gland M. Koleva*, D. Dikov *Department of General and Clinical Pathology, Medical Uni- versity of Plovdiv, Bulgaria; University Hospital “St. George’’ Plovdiv, Bulgaria Background & objectives: The current study investigates the rela- tion between prostatic eosinophilic metaplasia (EM) in a large series of cases with the basic prostate pathology in transurethral resection of the prostate (TURP) material. The study is supported by statistical analysis of the results. Methods: 61 TURP-specimens were reviewed for the presence of EM. Simultaneously BPH, BCH, PCa and National Institutes of Health-category IV prostatitis (so-called histologic prostatitis – HP -acute and chronic) were evaluated. Results: Prostatic EM was found in 34/61 cases (55.7%). This high frequency of EM in TURP correlated to the HP (p=0.000), BCH (p=0.000), and BPH (p=NA). No difference in patient’s age, clini- cal and laboratory data (PSA was found). Conclusion: The study presents the first attempt to quantify with statistical analysis the association between prostatic EM in a series of patients in the context of basic pathology in TURP-material. Our results enrich the available information about morphogenesis and relation between EM and other prostatic diseases. Сhronic inflammation (HP), persistent irritation (BPH) and BCH are basis of adult stem cells metaplastic conversion in some organ(prostate). The frequent combination between these processes is in favour of their unified molecular and cellular pathogenesis. E-PS-24-020 Sarcomatoid spermatocytic tumour: report of a rare case E. Dvindenko*, A. Dias, F. Santos, R. Cabrera *Instituto Português de Oncologia de Lisboa Francisco Gentil, Portugal Background & objectives: Spermatocytic tumour (ST) accounts for 1% of testicular germ cell tumours. It is an indolent neoplasm with good prognosis. Sarcomatous dedifferentiation may occur, portending an aggressive behaviour and representing a significant diagnostic chal- lenge that can lead to its misdiagnosis. Methods: Herein, we report the clinicopathological features of a case of sarcomatoid ST, initially misdiagnosed as malignant mixed germ cell tumour (MMGCT), which was referred to our institution with lung metastases exclusively composed of rhabdomyosarco- matous elements. Results: A 46-year-old man with bilateral lung metastases and a history of right radical orchiectomy for MMGCT (with teratoma, yolk-sac tumour and seminoma components) was referred to our institution for further therapy. Serum markers were all negative, and a lung biopsy was performed, reveal- ing a rhabdomyosarcoma. Slides of the testicular mass were reviewed and showed a high-grade spindle and rhabdmyo- blastic sarcoma with focal positivity for desmin, myoD1 and myogenin, and a minor component of spermatocytic tumour with colonization of peritumoral seminiferous tubules. A final diagnosis of sarcomatous ST with rabdhomyosarcomatous lung metastases was rendered. The patient developed brain metas- tases and underwent chemoradiotherapy and neurosurgery, but died 10 months after orchiectomy. Conclusion: ST is generally described as having an excel- lent prognosis. The presence of a sarcomatous component is a well-established event that renders a poor prognosis, despite aggressive systemic therapy and, as in this case, may be mis- interpreted as teratoma. In addition, colonization of seminifer- ous tubules can be mistaken with in-situ germ cell neoplasia. Awareness of this entity and its peculiarities is essential for its recognition and further adequate management of patients. E-PS-24-021 Incidentally discovered testicular metastatic tumour S. Makni*, W. Ben Makhlouf, C. Kammoun, S. Graja, S. Charfi, N. Gouiaa, C. Chaari, O. Boudawara *Habib Bourguiba University Hospital, Tunisia Background & objectives: Testicular metastatic carcinoma is a rare entity, often the primary is a prostatic adenocarcinoma. We report a new case incidentally discovered, to emphasize the importance of the examination of the testicles in the assessment of extension of prostatic cancer. Methods: An 82 year-old man followed for prostatic adenocarcinoma consulted for clotting and deglobulating haematuria. Physical examination finds a right testicular mass. An endoscopic resection with bilateral orchiectomy was performed for voiding and haemostasis. Results: The testicular examination showed an invasive carci- nomatous proliferation dissociating the seminiferous tubules made of clusters and patches of cells with some glandular structures leaning in cribriform massifs. The tumour cells have a similar appearance to those of the prostatic tumour; large cell with amphophilic cytoplasm and a very atypi- cal and highly mitotic nucleus with a prominent nucleolus. there are many lymphatic emboli. On immunohistochemistry, tumour cells were diffusely positive for CK and PSA. We con- cluded to the diagnosis of testicular metastasis of prostatic adenocarcinoma. Conclusion: Testicular metastases are very rare in known patients with prostate cancer. Careful physical examination through speci- men sampling and imaging of all the possible sites of metastasis are indispensable in the process of identifying metastasis. E-PS-24-022 Undifferentiated carcinoma with osteoclast-like giant cells in the renal pelvis: a very rare entity G. Moreno De Juan*, G.G. Yange Zambrano, A.K. Calapaqui Terán, P. Martín Soler, A. Azueta Etxebarría *Hospital Universitario Marqués de Valdecilla, Spain S354