ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 Methods: A total of 25 Luminal A like, 31 Luminal B like, 15 triple negative (TN) and 18 HER2 positive breast carcinomas were assessed for PRAME expression by immunohistochemistry (IHC) using the EPR20330 (ab219650; Abcam) monoclonal antibody. Expression of PRAME was quantified as positive (nuclear and/ or cytoplasmic staining) or negative, and also as a percentage of tumour cells expressing PRAME. Results: A significantly higher expression of PRAME was detected in HER2 positive carcinomas and TN breast carcinomas com- pared to ER positive (luminal like) subtype of breast carcinomas. PRAME expression was detected in 53% (8/15) TN carcinomas and 72% (13/18) HER2 positive carcinomas, as opposed to luminal A and B like breast carcinomas, where it was expressed in 32% (8/25) and 26% (8/31) of cases, respectively. Percentage of PRAME positive tumour cells showed positive correlation with tumour size, Ki67 proliferation index, HER2 status, nuclear grade and presence of metastasis, and negative correlation with ER status. Conclusion: Previous studies on PRAME in breast carcinoma were mainly based on RT-PCR detection, with immunohistochemical studies limited to polyclonal antibody results. Our study showed that HER2 positive and TN breast carcinomas more commonly express PRAME than ER positive carcinomas and that PRAME expression shows positive correlation with certain prognostic fac- tors. The importance of PRAME expression in breast carcinoma lies in its potential use as an immunotherapeutic target, particu- larly in patients with limited therapeutic options (e.g. in TN carcinomas). PS-01-003 Alpha-methylacyl-CoA Racemase (AMACR/P504S) over- expression occurs in the early proliferative lesions of the breast irrespective of apocrine differentiation Z. Gatalica, P. Stafford, S. Vranic* *Qatar University, Qatar Background & objectives: Alpha-methylacyl-CoA racemase (AMACR/P504S) is a mitochondrial and peroxisomal enzyme involved in the branched-chain fatty acid and bile acid metabo- lism. We explored AMACR expression in a large cohort of patients undergoing breast biopsies to investigate its role in cancer progression. Methods: The first, exploratory cohort of all cancer types (Caris Life Sciences) was investigated for AMACR mRNA expression followed by the second cohort of 150 patients’ breast biopsies (77 with invasive carcinomas) studied for the discrete lesions’ expression of AMACR using an automated IHC. The lesions were considered positive if AMACR was detected in ≥10% of the cells. Results: AMACR mRNA expression was detected in all cancer types and in breast carcinoma, its median value was substantially and consistently lower than in prostate carcinomas. However, AMACR protein expression was detected not only in apocrine carcinomas, as recently described, but also in normal breast epithelium (6/77 samples, 8%), and with increased frequency in proliferative epithelial lesions and carcinomas: 23% of UDH, 73% of ADH and in-situ carcinomas, 60% of invasive carcinomas, including lymph node/distant metastases. LCIS and invasive lobular carcinomas expressed AMACR in 50% of cases, respectively. Apocrine lesions showed strong, nearly uniform overexpression of AMACR (100% of metaplasias, hyperplasias, and in situ carcinomas and 88% of invasive apocrine carcinomas). Conclusion: AMACR expression in the breast is a common, early pathogenic event in the development of breast carcinoma and not exclusive to the apocrine morphology. It points to altered lipid metabolism as one of the hallmarks of breast carcinogenesis, simi- lar to several other malignancies, notably prostate carcinoma. It may hence represent a potential target for early cancer intervention and management. PS-01-004 Evaluation of NLRP3 immunohistochemical levels in breast cancer M. Lambropoulou*, V. Papadatou, A. Karatza, S. Tologkos, T. Deftereou, V. Lampropoulou, T. Alexiadis, I. Olbasalis, C. Alexi- adi, T. ChatzIneophytou, G. Tripsianis, O. Pagonopoulou *Histology-Embryology Lab., Medical Department, Democritus University of Thrace, Alexadroupolis, Greece Background & objectives: NLRP3 belongs to a complex of pro- teins triggering proteolytic degradation via caspase-1. This molec- ular pathway is involved in breast oncogenesis. The purpose of our research was the investigation of NLRP3 expression in breast cancer and its association with clinicohistopathological factors. Methods: Formalin-fixed, paraffin-embedded breast tissues from 43 patients were studied. 31 of them diagnosed with breast cancer (study group) and the other 12 (control group) diagnosed with fibroadenoma. NLRP3’s expression was inves- tigated immunohistochemically using a monoclonal anti-NLRP3 antibody. NLRP3 expression was statistically associated with various clinical and histological parameters using the SPSS program. Results: Our results showed statistically significantly higher expression of NLRP3 in well- differentiated carcinomas G3 (p<0.005), a tendency for higher NLRP3 expression in carcinomas with severe Ki-67 expression (p< 0.01) and also with the presence of lymph node metastases (p<0.022). In contrast, no statistically significant correlation was observed between NLRP3 expression and patient age (p=0.662), expression of ER (p=0.236) and PR (p=0.244), HER2 gene expression (p=0.342) and the cancer type (p=0.871). Conclusion: Based in our results, we conclude that NLRP3 could be a potential breast cancer biomarker as its high immunohisto- chemical expression is directly linked to advanced breast cancer. However, this is just a preliminary study and a more extended research needs to be conducted in order to establish these outcomes. PS-01-005 Encapsulated papillary carcinoma. Our experience from 2005 A. Córdoba*, R. Beloqui, I. Fernandez, C. Cerezo, A. Pasco, M.R. Mercado, I. Amat *Complejo Hospitalario de Navarra, Spain Background & objectives: The diagnosis of Encapsulated Papil- lary Carcinoma (EPC) of the breast is challenging. These lesions are staged as lesions in situ, and it is not possible to confirm EPC diagnosis until the capsule has been examined to rule out invasive growth. Methods: All the cases treated at our institution since 2005 are reviewed. To analyse the involvement of sentinel lymph nodes, as the indication for their study is controversial. We have collected 54 patients who were treated surgically for EPC. Selective SLN biopsy was performed in 39 (72%) of them. Results: We have observed that the mean size of EPC was 12 millimetres. The Nottingham grade was 1 in 46 cases (85.1%), 2 in 6 cases (11.1%) and 3 in 2 cases (3.7%). EPC was associated with invasive carcinoma in 17 cases (31.4%). Of the 39 patients in whom SN was performed, only three cases (5.5%) showed invasion, whereas one was ITC, and 2 micrometas- tases. In these three patients, the EPC showed invasion between 3 and 8 mm. S61