ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 (n=2) showed complete regression in post-NACT resection specimens. From core biopsy to resection, in terms of oestrogen receptor expression change, 8.9% (n=4) and 8.9% (n=4) of cases marked a decrease and increase, respectively. For progesterone receptor status, 33.3% (n=15) of cases demonstrated a decrease, while 11.1% (n=5) showed an increase. Conclusion: Changes in histologic grade, increased/decreased ER or decreased PR status have been described in literature as potential effects of NACT. Yet 11.1% (n=5) of our cases showed significant increase in PR status, which can better be explained by intratumoral heterogeneity and inadequate pre-NACT representa- tion of tumoral tissue. In fact these cases had significantly lower percentage (30%) of tumoral tissue representation in the pre-NACT core biopsy specimen. PS-01-020 Morphological and crystalchemical features of breast cancer microcalcificates O. Kolomiiets*, A. Piddubnyi, S. Danilchenko, R. Moskalenko *Department of Pathology Sumy State University, Sumy, Ukraine Background & objectives: The aim of the study is to study the main morphological and crystal chemical properties of microcal- cifications of breast cancer. Methods: In our study, we examined 30 specimens of breast carcer by histology (hematoxylin-eosin staining), histochemistry, scan- ning electron microscopy with EDS and TEM. Results: Histological examination of breast cancer samples revealed the presence of microcalcifications in the form of dark blue deposits of round and irregular shape, different sizes. A positive reaction to von Koss staining indicates the presence of calcium phosphate compounds in their composition. We confirmed the presence of round calcifications using SEM. SEM with X-ray microanalysis confirmed that the biomineral part of the samples of the group consists mainly of hydroxyapatites. In 6 cases, the presence of hydroxyapatite is combined with oxalates. However, oxalates and apatites had different localizations: apatites were associated with tumour, and oxalates were in intact adjacent tissue. Conclusion: We found the possibility of the simultaneous presence of microcalcifications of hydroxyapatite and oxalate nature in samples of invasive breast cancer. Different spatial localization of biominerals indicates different mechanisms and conditions for the formation of microcalcifications. PS-01-021 HER-2 ISH: do we need to count? S. Costache*, A. Baltan, A. Jurkiewicz, M. Porter, K. Billingham, H. Haynes, A. Chefani, S. Wedden, M. Sajin, C. D’Arrigo *Poundbury Cancer Institute, Dorchester, UK, Carol Davila Uni- versity of Medicine and Pharmacy Bucharest, Romania Background & objectives: Assessment of Her2 amplification requires counting 20-60 cells. This is time-consuming and may be unnecessary since morphological assessment can provide accurate diagnosis in a proportion of cases. We define parameters for selec- tion of cases that can be diagnosed morphologically. Methods: Using both glass slides and DP, we studied 200 consecu- tive breast core biopsies for which DDISH was requested following an indeterminate (2+) IHC result with 4B5. We assessed whole slides for presence and frequency of amplification clusters and polysomy of Ch17 by eyeballing. We separately performed formal counting and compared the time to reach a diagnosis. Results: We identified a number of morphological groups, includ- ing tumours with large amplification clusters (regardless of the number of Ch17 signals), tumours with sparse Her-2 signals (that are clearly below a ratio of 2 per Ch17) and tumours with high prevalence of borderline/non-amplified features. We evaluated con- cordance between morphological diagnosis and formal counting. Concordance was high in tumours with amplification clusters and in tumours with low gene copy numbers and/or low Ch17 signals. Concordance was poor in tumours with intermediate features. Time required for morphological assessment (30-60s) was 5-6 times faster than formal counting. For these assessments, DP was com- parable to glass slides. Conclusion: Some cases will still require the formal counting approach but we demonstrate that morphological assessment can be as accurate as formal counting in selected cases. For this to become established, training will need to be provided in order to ensure concordance amongst pathologists. This training can be delivered by DP. Digital programmes of Proficiency Testing would ensure continuing diagnostic alignment. This approach would save report- ing time and therefore Pathologists and Healthcare resources could be used more efficiently. PS-01-022 Pathological features of CT-guided bone lesion biopsy speci- mens in breast cancer patients M. Abramovic*, L. Korša, L. Grbanović, M. Čavka, I. Švagelj, M. Prutki, Z. Marušić *Clinical Department of Pathology and Cytology, University Hos- pital Centre Zagreb, Croatia Background & objectives: Current breast cancer guidelines recommend biopsy of metastatic lesions at presentation or first recurrence. Objective is to provide a cross-sectional pathological study of CT-guided bone biopsy specimens in breast cancer patients with suspicious bone lesions. Methods: A cross-sectional study on 56 consecutive female breast cancer patients who underwent CT-guided biopsy of suspicious bone lesion was performed. Quantity of the specimen was defined as optimal (>5% cancer cellularity), suboptimal and low (non- diagnostic). Immunophenotype of the primary tumour and matching metastasis was compared, where available. Diagnostic accuracy of CT-guided bone biopsy was determined. Results: A total of 58 bone lesions were biopsied in 56 patients and 44 (75.9%) breast cancer metastases were found. CT-guided biopsy enabled optimal quantity of specimens in most cases (56.9%), followed by suboptimal (32.8%) and low (10.3%). In 10% of positive cases, the number of tumour cells was too low for further immunohistochemical analysis. In 36 paired cases (primary vs metastatic), a shift in immunophenotype was observed in 13 cases (36.1%), most commonly from PR-positive to PR-negative (10/13, 76.9%). Sensitivity of CT-guided biopsy for detecting bone metastases was 93.6% and specificity was 100%. Conclusion: CT-guided bone biopsy is a method with high sen- sitivity and specificity for detecting breast cancer metastasis that can be used when soft tissue metastatic lesions are not obtainable. The proportion of positive cases with sufficient tumour quantity for further immunohistochemical analysis is high. Comparison of primary tumour and metastasis immunophenotype revealed dis- cordance in more than one third of patients, with potential thera- peutic implications. PS-01-023 Luminal breast cancer subtypes and associated prognostic fac- tors: a population-based study from Osijek, Croatia S66