ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 G. Kalodimos*, G. Kitsakis, P. Skoufogiannis, G. Tsiouma, A. Feritsean, S. Divani *General Hospital of Volos, Greece Background & objectives: To determine the cytologic interpretation as well as various differential diagnostic problems of Hashimoto’s thy- roiditis that is the most common form of thyroiditis. Methods: We analysed data on 93 patients with nodular or dif- fuse palpable enlargement of the gland, who underwent fine nee- dle aspiration and were diagnosed with Hashimoto’s thyroiditis. Thyroid hormonal assay and antithyroid antibody levels were evaluated. Results: Hurthle cells mostly in tissue fragments were present in all cases and the cellularity was variable. Histiocytes with phagocytic debris were present in 9 cases(9,6%), whereas follicular cells with- out follicular pattern in 22(23,6%). All cases showed lymphocytes and occasional plasma cell and immunoblasts. Colloid was absent. Coexistence with papillary carcinoma confirmed by histology was found in6 (6,66%) female patients Laboratory examination revealed high levels of TSH and anti-peroxidase antibodies in all malignant cases. In 4(4,3%) patients a differential diagnosis with non Hodgkin lymphoma was taken into account but immunocytology confirmed the reactive nature of the lymphocytes. Conclusion: Hashimoto’s thyroiditis diagnosis can be achieved in the majority of cases. Careful interpretation of fine needle aspiration material and correct evaluation of all cytomorphologi- cal findings are required in order to minimize potential pitfalls. Papillary carcinoma and non Hodgkin lymphoma have to be ruled out in some cases. The differential diagnosis includes also fol- licular and Hurthle cell neoplasms. PS-11-007 Mediastinal metastases diagnosed by endobronchial ultra- sound-guided transbronchial needle aspiration. Beyond lung cancer metastases P. García Abellás*, R. Meléndez Gispert, A. Ferrer Gómez, A. Caminoa-Lizarralde Aiza, A. Benito Berlinches *Ramón y Cajal University Hospital, Spain Background & objectives: Endobronchial ultrasound-guided trans- bronchial needle aspiration (EBUS-TBNA) is increasingly used in the diagnostic and staging of mediastinal lymph node metastases. The cyto- logical diagnosis of metastases from extrapulmonary primaries can be challenging if we only consider a pulmonary origin. Methods: A retrospective review of EBUS-TBNA specimens with clinical and radiological diagnosis of mediastinal lymph node metas- tases (PET-CT SUV max >2,5) from the Pathology Department files of our institution between 2018-2021 was performed. In total, 179 patients were included. In all cases, an immunocytochemical study was done in order to determine the origin of the neoplasm. Results: A lung origin was confirmed in 146 of the studied cases (81.5%). The diagnosis of the cases with an extrathoracic primary tumour was confirmed in 19 cases (10.6%). Metas- tases of mammary (n=6); prostate (n=2); colorectal (n=2); urothelial (n=3) and mesenquimal(n=2) origin were observed. Despite the complementary studies, a definitive origin could not be reached in 14 cases. Enteroid pattern adenocarcinomas (n=1) and squamous adenocarcinomas in patients with a previ- ous history of primary urothelial (n= 3) and cervical neoplasia (n=2) supposed a difficult differential diagnosis. Also muci- nous neoplasms mimicking a gastro-biliary-pancreatic origin (n=3), acinar patterns (n=2) resembling prostate adenocarci- nomas and neuroendocrine neoplasm without known primary (n=3) implied a diagnostic challenge. Conclusion: Advanced target therapies in lung cancer force pathologists to optimize the material obtained in EBUS-TBNA procedures for molecular study. A comprehensive review of the cytological features may help recognising the origin of the neo- plasm. However, an holistic view of the patient clinical history and immunocytochemical or even molecular techniques are also needed, specially if extrathoracic metastatic cases are suspected. PS-11-008 Programmed Death Ligand 1 (PD-L1) expression in fine needle aspiration cell blocks of head and neck squamous cell carcinoma and its cytohistological concordance S.K. Lou*, H. Ruff, C. Cheung *University Health Network, Canada Background & objectives: PD-L1 immunoexpression in head and neck squamous cell carcinoma (HNSCC) determines immu- notherapy eligibility. Patients are often diagnosed using fine needle aspiration (FNA) of metastatic lymph nodes, however, the cytohis- tologic correlation of the combined positive score (CPS) is largely unknown. Methods: This study retrospectively identified 43 patients, between 2016 and 2020, with HNSCC diagnosed on surgical (SpS) and cytologic specimen (CyS). Slides were reviewed and cases with <100 tumour cells or if the block was missing, were excluded. This resulted in 36 cytology cell blocks and 39 surgical tissue blocks for PD-L1 immunohistochemistry (22C3 clone). All cases were scored with CPS. Results: The CPS (<1%/≤20%><!--1-->20%) for the SpS and CyS were as follows: 2(5.9%) /17(50.0%) /15(44.1%) and 10(29.4%) /11(32.4%) /13(38.2%), respectively. There was a total of 34 case pairs, composed of 13 pairs with matched site (neck lymph nodes) and 21 pairs with the primary site of SCC (biopsy/resection) and corresponding FNA of lymph node metastasis. There was fair over- all agreement (OA) of 76.5% (k=0.261) at a CPS cut-off of 1%. The OA did not differ significantly between the case pairs with matched and unmatched sites (p=0.4653). CyS has a specificity and positive predictive value (PPV) of 100%, but only a sensitivity of 75% and negative predictive value of 20%. Conclusion: PD-L1 immunohistochemistry assessment on CyS only shows fair agreement with its surgical counterpart. However, CyS demonstrates high PPV with no false positive results based on our limited study. This needs further evaluation as our study are low in case with negative CPS (<1%). In the event of a negative CPS on CyS, a reassessment of PD-L1 on a surgical/histological specimen should be attempted due to the chance of a false nega- tive result. PS-11-009 Association of high-risk HPV strains other than 16 and 18 with progression from atypical squamous cells of undetermined significance to worse abnormal cervicovaginal cytology over a 5-year period: results from a single academic institution T. Giorgadze*, A. Grover, M. Ratiani, C. Onyenekwu, M. Molina, P. Jain *Medical College of Wisconsin, USA Background & objectives: Cervical cancer is the fourth most common cause of cancer in women. We aimed to assess association of high-risk HPV strains (other than 16 and 18) with progression from atypical cells of undetermined significance (ASCUS) to worse cervicovaginal cytology. S123