ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 22C3 and SP263 clones in all defined cutoffs (K>0.8), taking into consideration the histologic and sample types. Conclusion: Excellent concordance was observed comparing 22C3 PD-L1 LDT and SP263 IVDR assays. SP263 assay seemed to be more consistent across histologic types. Validation, quality control, training, and experience are essential, especially in LDT, and may explain the high concordance observed. Considering the need of IVDR tests in the future, our work demonstrated an excellent con- cordance between SP263 IVDR and 22C3 LDT assays, ensuring the reliability of the former when considering a switch. PS-16-013 Histopathologic patterns in brain metastases of lung adenocar- cinoma: does it affect the survival? L.D. Micoogullari, E. Cakir, I. Guzelis*, F. Cakalagaoglu, A. Kahraman *Izmir Katip Celebi University, Turkey Background & objectives: Primary lung adenocarcinoma is classified and graded according to histopathological patterns. The main goal of our study is to evaluate the prognostic impact of these patterns in surgi- cally resected brain metastases of lung adenocarcinomas. Methods: A retrospective review of patients with histopathologic diagnoses of brain metastatic lung adenocarcinoma between the years 2010-2022 was made. The presence and percentage of his- topathological patterns including acinar, papillary, solid, micro- papillary, cribriform, and complex glandular were noted. A total of 88 patients with brain metastasis of lung adenocarcinoma were included in the study. The mean age was 60.7±9.2 years. Results: As ALK, ROS, and BRAF mutation was performed on 31, 29, and 4 patients respectively, none of them were mutated. However, as EGFR mutation was evaluated in 31 patients, 4(12.9%) of them were mutated. Predominant patterns of the tumours were; solid 49 (55.7%), papillary 13 (14.8%), cribri- form 11 (12.5%), complex glandular 8 (9.1%), micropapillary 4 (4.5%), acinar 3 (3.4%). Predominant patterns were not associ- ated with overall survival in the long-rank test (p=0.87). The age of 55 was found as a cut-off associated with poor overall survival (p=0.029). TTF-1 positivity was found to be associ- ated with better overall survival (p=0.008). Filigree pattern, a micropapillary subtype, was associated with EGFR mutation (p=0.05). Conclusion: Future studies with larger series are needed to demon- strate the prognostic significance of the histopathological patterns observed in brain metastases of lung adenocarcinomas. PS-16-014 Regional variability and prognostic value of tumour budding in pulmonary squamous cell carcinoma M. Maillard*, C. Neppl, J. Anex, P. Zens, S. Peters, T. Krueger, S. Berezowska *Institute of Pathology, Lausanne University Hospital (CHUV), Switzerland Background & objectives: Grading pulmonary squamous cell carci- noma (pSQCC) is controversial. Tumour budding (TB) is a prognostic biomarker in colorectal carcinoma, but its significance in pSQCC is unclear. We compared inter-region variability of TB and its prognostic value in pSQCC. Methods: We retrospectively included 249 patients resected at the University Hospitals Bern (2000-2013) and Lausanne (2005- 2020) with available tissue from diagnostic biopsy and surgical specimen. TB was scored on H&E-stained slides according to the CRC consensus criteria at the tumour centre (TC), infiltration front (IF) and in the biopsy (B). Associations of TB with clinico- pathological parameters and survival were assessed. Results: TB was low (0-4 buds/0.785 mm2) in 128 (IF), 119 (TC) and 184 (B), intermediate (5-9 buds/0.785 mm2) in 68 (TC), 65 (IF) and 34 (B) and high (≥10 buds/0.785 mm2) in 51 (TC), 65 (IF) and 26 (B) cases. Both the absolute number of buds and the TB score (1 to 3) were similar when comparing TC and IF (pbuds = 0.194, pscore = 0.383) but significantly different when comparing TC and B (pbuds < 0.001, pscore < 0.001). Only TB scored at the IF showed prognostic potential regarding 5-year overall survival (p = 0.045), which was mainly driven by a poorer survival of patients with high TB scores. Conclusion: IF and TC were comparable but only TB assessed at the IF showed prognostic significance. Furthermore, TB assessed in biopsies was different from resections, limiting the use of bud- ding as a preoperative prognostic marker. PS-16-015 Another retrospective study to throw more light on prognostic implications of STAS (tumour spread through air spaces) in lung adenocarcinoma S. López-Muñoz*, L. Gutiérrez-Sainz, I. Losantos-García, P. Cruz-Castellanos, O. Higuera, J. de Castro-Carpeño, M.I. Esteban-Rodriguez *Department of Pathology, University Hospital La Paz, Madrid, Spain Background & objectives: STAS is a recently described prognostic factor mostly studied in lung adenocarcinoma, although the concern it could represent a grossing artifact remains. This study aimed to assess the clinical implications of STAS in lung adenocarcinoma. Methods: We retrospectively reviewed 118 cases of lung adenocar- cinoma from 2015 to 2018 at La Paz University Hospital, Madrid (Spain). The distance from the edge of the tumour to the farthest STAS was measured and the cutoff for this distance was assessed by ROC curves. RFS and OS were compared considering presence of STAS and distance of STAS. Results: STAS was found in 68,6% of adenocarcinomas. Patients with STAS had shorter median RFS (52,7 months) than patients without STAS (70,2 months) [p=0,028], showing a 2,29 times greater risk of recurrence (HR=2,29; p=0,03). Multivariant analy- sis with histological grade 3 adenocarcinomas showed no statistical significance. Two possible cutoffs of 1,5 or 2,5 mm from the edge of the tumour to STAS were established. RFS and OS were shorter when STAS was farther than 1,5mm (p=0,045 and p=0,05), with a 2,06 times greater risk of death (HR=2,06; p=0,05). Statistical significance was found only in OS for a 2,5mm cutoff (p=0,013) and risk of death was 2,39 greater (HR: 2,39; p=0,01). Conclusion: STAS is a predictive factor of recurrence risk mostly associated with high-grade lung adenocarcinomas and should prompt pathologists its identification in surgical specimens of lung cancer. A cutoff of 1,5mm for assessing distance of STAS to the tumour margin could be acceptable. Further investigations are needed to validate these cutoffs and prognostic implications of STAS in other histological types of lung cancer. PS-17 | Poster Session Thymic and Mediastinal Pathology S153