ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 more gene amplification studies are required to be done in the cases showing positive expression (3+) of HER2 for choosing potential candidates for HER2- targeted therapy. PS-26-013 Two cases of primary intratesticular rhabdomyosarcoma I. Elouarith*, F. Zouaidia, A. Jahid, Z. Bernoussi, K. Znati *Ibn Sina University Hospital Centre, Morocco Background & objectives: Intratesticular Rhabdomyosarcoma is a rare malignant tumour showing skeletal muscle differentiation. The importance of this paper is to emphasize the importance of macroscopic examination in confirming intratesticular location and to highlight the importance of Immunohistochemical study for the diagnosis. Methods: 16 and 18 years old patients, with no medico-surgical or trauma history, consulted for painless scrotal mass gradually increasing in size. Scrotal ultrasound revealed, in both patients, suspect intratesticular mass. So, they underwent inguinal orchidec- tomy. Pathology results were consistent with the diagnosis of intrat- esticular embryonal rhabdomyosarcoma grade III of FNCLCC. Thereafter, the two patients received chemotherapy. Results: Rhabdomyosarcoma is a malignant mesenchymal tumour showing skeletal muscle differentiation. Four types have been described in the 5th edition of WHO classifications of soft tissue and bone tumours. The most common histological subtype is Embryonnal-rhabdomyosarcoma. Primary intratesticular localization is very rare and must be differentiated from paratesticular locations. This distinction must be made during the per-operative period and while the macroscopic examination of the surgical specimen. The Immunohistochemical study is essential for diagnosis and to exclude other intratesticular spindle cell sarcomas and germ cell tumours. The optimal treatment is based on radical inguinal orchiectomy and adjuvant chemotherapy. Tumour size, age, histological type and lymph node involvement are important risk factors. Conclusion: Rhabdomyosarcoma is a highly aggressive neoplasm occurring frequently in children and young adults. Intra-testicular localization remains exceptional and very few cases have been reported in the literature. Diagnosis of ITRMS is based on anatomopathological examination. Surgery and chemotherapy remain the mainstay of treatment. Radiotherapy is useful for local recurrence and metastasis. PS-26-015 Intraductal carcinoma of the prostate in low-risk patients does not affect PSA failure and treatment decisions R. Semba*, K. Uchida, T. Shiraishi, T. Onishi, T. Sasaki, T. Inoue, M. Watanabe *Pathology / Mie University Hospital, Japan Background & objectives: Intraductal ductal carcinoma of the pros- tate (IDCP) is an independent poor prognostic factor for prostate cancer (PC) and known to be associated with adverse features. However, its significance in low-risk patients is poorly understood and was inves- tigated in this study. Methods: 866 cases of radical prostatectomy were performed between 2012 and 2021, of which 116 cases were low-risk PC preoperatively according to the EAU guidelines. Of these, 112 patients were enrolled, excluding 4 cases who received preopera- tive hormone therapy. Evaluation factors were clinicopathological characteristics of patients, and PSA free survival. The evaluation of IDCP and various pathological factors followed WHO. Results: Of 112 patients, 12 (10.7%) had IDCP. PSA failure was observed in 4 of 112 patients (IDCP-: 3, IDCP+: 1). There were no significant differences in age, PSA and PSAD between patients with and without IDCP (age: p=0.432, PSA: p=0.7, PSAD: p=0.84). The occurrence of extraprostatic extension (EPE) and radial margin (RM), factors influencing treatment decisions, also did not differ between the two groups (EPE: p=0.172, RM: p=0.171). PSA free survival with and without IDCP demonstrated no significant differences (log-rank test: p=0.475). Conclusion: Low-risk patients were found to have a better prog- nosis even when IDCP was detected in surgical specimens. In the low-risk group, IDCP may not affect PSA free survival. In addi- tion, IDCP does not influence treatment decisions, as there is no difference in the incidence of EPE or RM with or without IDCP. These results also reaffirm the utility of active surveillance. The incidental finding of IDCP in low-risk patients is nothing to fear. PS-26-016 Papillary renal cell carcinoma (PRCC): a single institution archive review of morphological variability in the light of the new WHO 2022 classification T. André Sousa Oliveira*, O. Hes *Department of Pathology - Hospital de Santa Maria, CHULN, Portugal Background & objectives: The diagnostic approach to PRCC has changed substantially following the release of the new WHO Classifi- cation 2022 and the type 1 and 2 subtyping is no longer recommended. Herein, we map the variability of PRCC in a single institution archive. Methods: We reviewed all reports of PRCC cases from a tertiary healthcare institution from a 10-year period [2012-2021], totalling 616 cases. Morphologic parameters, TNM stage, WHO/ISUP nuclear grade, immunohistochemical profile, and molecular study results were re-evaluated according to new WHO criteria. If available, patient’s sex and age; tumour laterality, multifocality, size, presence of necrosis, and invasion of stage-defining structures were recorded. Results: The most common subtype was PRCC NOS (39.9%), followed by classic PRCC (previously type 1) [35.9%], oncocytic (12.3%), biphasic squamoid (6.0%), mucin-producing (3.2%), solid (1.1%), reverse polarity (0.6%) and Warthin-like (0.8%). The mean patient age was 63 years and the male to female ratio was 2.6. Average tumour size was 49 mm. Overall, PRCC presented at an early stage in 79.3% of cases and out of the advanced stage cases, 77.6% were classified as PRCC NOS. Cytokeratin 7 was consist- ently expressed in most types, at times focally, with the exception of Oncocytic and NOS types which were negative in 29.4% and 44.2% of cases, respectively. Conclusion: PRCC remains a highly heterogeneous group of renal tumours that will benefit from further studies aimed at subclas- sification and validation of clinical utility, as well as well-defined criteria. Just as important, PRCC’s variability makes it a common mimic of other renal cell carcinomas (RCC), namely molecularly defined RCC (FH- or SDH-deficient and ALK- or TFE3-rearranged RCC), collecting duct carcinoma, oncocytic renal neoplasms and mucinous tubular and spindle cell carcinoma. Adequate immuno- histochemical and/or molecular studies should resolve most diag- nostic doubts. PS-26-017 Pathological characterisation of Bosniak III and IV renal cysts R. López del Campo*, L. Rodríguez-Carunchio, K. Saez De Gor- doa, S. Jiménez, C. Sebastià, T. Ajami, M. Musquera, I. Trias *Hospital Clínic i Provincial, Spain S171