TY - JOUR T1 - Update regarding the role of PD-L1 in oncocytic thyroid lesions on cytological samples JF - Journal of Clinical Pathology JO - J Clin Pathol DO - 10.1136/jclinpath-2022-208215 SP - jclinpath-2022-208215 AU - Marco Dell'Aquila AU - Pietro Tralongo AU - Alessia Granitto AU - Maurizio Martini AU - Sara Capodimonti AU - Mariangela Curatolo AU - Vincenzo Fiorentino AU - Alfredo Pontecorvi AU - Guido Fadda AU - Celestino Pio Lombardi AU - Maco Raffaelli AU - Liron Pantanowitz AU - Luigi Maria Larocca AU - Esther Diana Rossi Y1 - 2022/06/14 UR - http://jcp.bmj.com/content/early/2022/06/14/jclinpath-2022-208215.abstract N2 - Aims Several papers have shown that programmed death-ligand 1 (PD-L1) expression is a relevant predictive biomarker in anti-PD-L1 cancer immunotherapy. While its role in several human cancers is correlated with poor prognosis and resistance to anticancer therapies, in thyroid cancers the role of PD-L1 remains questionable. Few articles have studied PD-L1 in thyroid fine-needle aspiration cytology (FNAC), demonstrating a possible correlation with papillary thyroid carcinoma. However, its role in oncocytic thyroid lesions remains controversial. We accordingly examine the performance of PD-L1 immunostaining in liquid based cytology (LBC) from oncocytic lesions.Methods From January 2019 to March 2021, 114 thyroid lesions diagnosed by FNAC from lesions with a predominant oncocytic component, were enrolled for evaluation by PD-L1 immunostaining on both LBC and corresponding histology samples.Results The FNAC cohort included 51 benign (B, negative controls), 4 atypia of undetermined significance/follicular lesions of undetermined significance (AUS/FLUS), 57 follicular lesions (follicular neoplasm/suspicious for FN, FN/SFN) and 2 suspicious for malignancy (SFM) cases. Fifty-four cases (11B, 2 AUS/FLUS, 39 FN/SFN and 2 SFM) had histological follow-up including: 1B case resulted as a hyperplastic oxyphilic nodule in Hashimoto thyroiditis (HT), 10B as goitre, 2 AUS/FLUS cases as oncocytic adenomas (OAs); 39 FN/SFN included 27 OAs, 4 FA and 8 oncocytic follicular carcinoma (OFC). The two SFM cases were diagnosed on histopathology as OAs. Increased plasma membrane and cytoplasmic PD-L1 expression were found in 47 cases of the LBC cases (41.2%). Among the histological series, 67.3% of OAs and 75% of OFC had PD-L1 expression, while negative PD-L1 was found in hyperplastic oncocytic cells in HT. A positivity in more than 30% of the neoplastic cells was found in 72.9% of the cases including six OFC.Conclusions These data suggest that PD-L1 expression is expressed in oncocytic thyroid lesions. While weak PD-L1 expression failed to discriminate benign from malignant lesions, OFC demonstrated more intense cytoplasmic and membranous expression.All data relevant to the study are included in the article. ER -