ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 Background & objectives: Frozen section (FS) histology is the most commonly used method for intraoperative evaluation of the lung lesions, however it requires significant capacity in equipment, staff and time. Imprint cytology (IC) is a fast, cheap and reliable alternative. Methods: The retrospective study included 193 patients who were hospitalized to clarify aetiology and treat the infiltrative lung lesion. During the diagnostic/therapeutic surgery, tissue sample was obtained and imprint was taken. The samples were processed as standard pro- cedure for FS histological analysis. Sensitivity, specificity, positive and negative predictive value for determining adenocarcinoma were calculated in a relation to final pathohistological diagnosis. Results: Sensitivity, specificity, positive and negative predictive value for IC were, respectively, 89,86%, 100%, 100% and 94,66%, while the same parameters on FS were, respectively, 94,2%, 100%, 100% and 96.86%. The adequacy of IC was 96,37%. Cytologi- cal findings, of later proven adenocarcinomas, were characterized as adenocarcinomas (33,33%), NSCLC-NOS (11,59%), malig- nant tumour (44,93%), benign tumour (2,90%), non-diagnostic (1,45%), and inadequate (5,80%). Average area of lesion section from which imprint was taken was significantly higher in lesions whose findings were characterized as adenocarcinoma, compared to the findings characterized as malignant (p=0,025). There wasn’t statistically significant difference in average area of lesions sec- tion between the true positive and false negative IC findings of adenocarcinoma. Conclusion: IC provides a reliable alternative to the traditional histological diagnosis in the intraoperative evaluation of lung ade- nocarcinoma. The area of the section wasn’t significant factor in intraoperative diagnosis of adenocarcinoma by IC. PS-16-006 Pulmonary adenofibroma: a clinicopathological analysis of a case series C.M. Vieru*, Y. Gómez Navarro, T. Labiano Miravalles, A. Panizo Santos, M. Garcia Martos *Hospital General Universitario Gregorio Marañón, Spain Background & objectives: Pulmonary adenofibroma (AF) is an extremely rare benign tumour not yet described in the WHO classifica- tion of lung neoplasms. It is frequently misdiagnosed as solitary fibrous tumour. Approximately 40 cases have been described. Methods: We searched the pathology archives of two major univer- sity Spanish hospitals for cases of pulmonary AF over a period of 10 years (2012-2022). We retrospectively analysed clinical, radio- logical, histopathological and immunophenotypic features. Results: Our series included five cases middle aged (35-68 years) with male preponderance (4 male and 1 female). All cases were detected incidentally on radiology as a solitary well-defined lung lesion with a diameter ranging from 0,5 to 2,5 cm. Grossly they were whitish with a smooth surface. Histological examinations revealed biphasic tumours with epithelial component with gland- like spaces lined by respiratory epithelium, surrounded by a stromal component with spindled-cell fibroblastic or myofibroblastic proliferation. There were not necrosis, atypia or signs of malignant transformation. Immunohistochemistry studies were performed and all were EMA and TTF1 positive in the epithelial component and actin positive in the stroma. STAT6 resulted negative in all cases. Conclusion: Pulmonary adenofibroma is a rare benign pulmonary tumour whose morphological pattern could be mimic by various lung tumours. Breast and pulmonary AF show a significant over- lap of their morphological characteristics. Biphasic morphology and immunohistochemistry are helpful to distinguish it from other potentially aggressive tumours like solitary fibrous tumour. PS-16-007 Use of insulinoma-associated protein 1 in small biopsy samples of small cell lung carcinoma (SCLC) S. Glumac*, M. Jovanovic, R. Janković, S. Popevic, M. Stjepanovic, B. Dozic * Institute of Pathology, Faculty of Medicine, University of Bel- grade, Serbia Background & objectives: Recent publications point out that insu- linoma-associated protein 1 (INSM1), as nuclear marker, demonstrates superior performance to the individual and combined use of synapto- physin (Syn), chromogranin A (ChA) and CD56 for diagnosing neu- roendocrine tumours of lung. Methods: Retrospectively reviewed small biopsy samples of pre- viously diagnosed SCLC at the Institute for pathology, Medical Faculty, University of Belgrade. Immunohistochemistry was per- formed using mouse monoclonal INSM1 antibody (Santa Cruz Biotechnology, Dallas; clone A-8). Positivity was assed as clear nuclear reactivity, and the intensity of immunoreactivity (1+, 2+, 3+) combined with percentage of positive cells (0% to 100%). Results: A total of 62 eligible cases in the period of 2019-2021 were reviewed. An initial standard IHH panel, based on neuroendo- crine morphology, for all cases included S, CD56, TTF-1 and Ki-67. Four cases (6.5%) were negative for S, focally or diffusely positive for CD56 in initial ICH panel, and negative for INSM1. Two cases (3.2%) were negative for all three markers. Another four cases were negative for S, but showed focal or diffuse CD56 positivity, and all were strongly positive for INSM1. The rest of cases (83.9%) were positive for all three markers; S and CD56 with variably immuno- expression, while INSM1 showed strong immunoexpression. Conclusion: Having in mind that in pulmonary pathology “tissue is issue”, and a need to preserve any tissue collected or further molecular testing, it is recommended to use as less as possible IHC markers to post accurate and precise pathologic classification possible. In our work, INSM1 showed good concordance related to immunoexpression of membranous markers. Thus, use of single IHC marker, which is nuclear and more specific than two membra- nous markers, could save time and tissue for further testing as well. PS-16-009 Clinicopathologic and molecular characteristics in ERBB2 (HER2)-altered non-small cell lung cancer Y. Lee*, B. Lee, Y. Choi *Department of Pathology and Translational Genomics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea Background & objectives: Anti-ERBB2 therapies have been proven to be effective in ERBB2-altered cases of non-small cell lung cancer (NSCLC). The goal of this study is to demonstrate the clinicopatho- logic and molecular features of ERBB2-altered NSCLC to enrich the potential candidates. Methods: We found 66 cases of ERBB2-altered NSCLC including 28 amplified [copy number (CN) ≥ 4] and 41 mutated cases from the next-generation sequencing (NGS) data of 969 NSCLC patients tested from 2018 to 2021. Their clinicopathologic data and tissue slides were reviewed. Immunohistochemistry (IHC) and silver in situ hybridization (SISH) were performed and assessed referring to the breast cancer guideline. Results: SISH-confirmed ERBB2 amplification and oncogenic ERBB2 mutation were identified in 24 and 41 patients, respec- tively. They were all in advanced stages (≥ III, AJCC, 8th). They mostly demonstrated adenocarcinoma with micropapillary pattern S151