ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 prostate cancer, specifically compared to normal tissue and benign changes. Our findings are important for further research on the innervation of human prostate cancer and its possible applications. Funding: Supported by VEGA grant VEGA 1/0684/21 E-PS-24-037 Undescended testis associated with seminoma and persistent Mullerian duct syndrome F. Karasavvidou, M. Strataki*, V. Tsangari, G. Kabanos, N. Kolitsas, M. Ioannou *Department of Pathology, Faculty of Medicine, School of Health Sciences, University of Thessaly, Greece Background & objectives: Male sex differentiation is driven by tes- tosterone and anti-mullerian hormone (AMH) for the regression of Mullerian ducts in foetuses. Mutations inactivating AMH or its receptor AMHRII lead to rare Persistent Mullerian Duct Syndrome (PMDS) in otherwise normally-virilized 46, XY males. Methods: A 21-year-old man was referred to a urologist for right cryptorchidism, an early clinical sign of PMDS. Laparoscopy revealed the atrophic testis in the inguinal canal attached to the uterus. Excision of the testis and uterus was done. We received tes- tis (1.5x1.2x1 cm), spermatic cord (3 cm), an attached hypoplastic uterus (2.5x1.2x1 cm), and a fallopian tube (4 cm). Results: Microscopically, the testis was atrophic with marked loss of germ cells, and with classical seminomatous germ cell tumour measured 1.3 cm. Cut sections of the uterus and fallopian tube showed the classical histology of these organs. Conclusion: Though rare, every surgeon operating upon inguinal her- nia or undescended testes, or cryptorchidism needs to know about the presence of the uterus in a phenotypic male patient at any age. A high degree of suspicion and awareness is needed to diagnose this condition. Patients with PMDS are at higher risk of testicular malignancy than patients with isolated undescended testis. Early treatment is needed to maintain fertility and prevent the occurrence of malignancy in the testis or in remnant Mullerian structures. E-PS-24-038 Collecting duct carcinoma, a great mimicker - a case report of a rare neoplasia and literature review M. de Brito Pereira*, A. Alves, E. Vitorino, A. Canastra, A. Beltran *Pathology Department, Hospital CUF Descobertas, Lisbon, Portugal Background & objectives: Collecting duct carcinoma is a high-grade renal neoplasia, presumably arising from the Bellini ducts. It accounts for less than 1% of renal malignancies, yet the clinicopathological over- lap with other high-grade malignancies makes the incidence of this lesion difficult to ascertain. Methods: We report the case of a 69-year-old male without previ- ous history of neoplastic lesions that presented in our institution with a history of gross haematuria. At admission, an imagologi- cal evaluation was performed that revealed a cystic lesion with an internal solid component in continuity with the cystic wall. This lesion was classified as Bosniak IV. A tumorectomy was then performed. Results: The superior pole of the kidney was occupied by a cystic lesion with a smooth surface. In section, a solitary white papillary projection was identified in the interior component of the cyst. The projection had continuity from the parenchyma to the adipose tissue. Histologically, the lesion was adjacent to the renal medulla with a solid and tubo-papilary architecture and an desmoplastic infiltrating component. Composed of cuboidal cells, with eosinophilic cytoplasm and large nuclei with prominent nucleoli. Sarcomatoid differentiation was also present. The cells expressed diffuse positivity for PAX-8 (strong) and GATA3 (weak); negativity for p63, CK5, CK7, CA IX, CD117 e CD10. The diagnosis of collecting duct carcinoma was made. Conclusion: Other clinicopathological overlapping entities, such as fumarate hydratase-deficient renal cell carcinoma, papillary renal cell carcinoma, mucinous tubular spindle cell carcinoma with high-grade transformation, high-grade unclassified renal cell carcinoma and metastatic carcinoma, must be considered in the differential diagnosis and excluded. At the time of this report, the patient presents no signs of disease progression. E-PS-24-039 Divergent infiltrating high grade urothelial carcinoma with small cell neuroendocrine carcinoma differentiation A. Sykaras, S. Stefanakis, C. Kouvidou* *Department of Pathology, Evangelismos General Hospital, Ath- ens, Greece Background & objectives: Approximately 25-30% of urothelial car- cinomas (UC) show divergent differentiation that includes urothelial and non-urothelial (squamous, glandular or neuroendocrine) histologi- cal variants. The vast majority of bladder neuroendocrine carcinomas (NECs) are usually admixed with a non-neuroendocrine component, mostly infiltrating UC. Methods: A 60-year-old man presented with painless gross haema- turia and CT and cystoscopy revealed an exophytic mass localized at the dome of the bladder. A transurethral resection of bladder tumour (TURBT) was performed and the surgical specimen was entirely submitted for microscopic examination in the pathology lab. Results: Histological examination revealed a high-grade muscle- invading UC with tumour cells arranged in nests and sheets. Inter- estingly, four neoplastic foci had distinct morphological features and the typical appearance of small cell neuroendocrine carci- noma (SmCC). Immunohistochemical analysis revealed that the SmCC component had a proliferation marker Ki-67 labelling index above 90% and expressed CD56 and CD117 but was negative for other neuroendocrine markers (chromogranin, synaptophysin and INSM1) and for TTF1 and LCA. On the contrary, the UC compo- nent displayed focal and weak expression of CD117 and was CD56 negative. Moreover, both the SmCC and UC components showed aberrant expression (strong and diffuse) of p53, overexpression of p16 and loss of RB1. Conclusion: Although the presence of SmCC mixed with other bladder neoplasm should always be reported, it is controversial if the diagnosis should reflect the percentage of the SmCC component. We avoided the term “mixed SmCC-UC”, following the definition of mixed neuroendo- crine-non neuroendocrine neoplasms (MiNENs). Instead, the term “UC with SmCC differentiation” was used to highlight the focal distribu- tion of the neuroendocrine component. The expression profile of p53 and RB1 classifies this tumour in the neuroendocrine-like molecular subtype of muscle-infiltrative bladder cancer. E-PS-24-040 Temporal bone metastasis revealing a papillary renal cell carcinoma S. Moussa*, A. Bdioui, S. Mestiri, A. Baccouche, O. Belkacem, W. Majdoub, S. Hmissa S359