FNAC (Fine needle aspiration cytology) and histopathological correlation and reclassification of thyroid neoplasm in accordance with WHO classification 2022

Abstract

While assessing whether a patient requires surgery or conservative treatment, the thyroid FNAC is crucial. “The Bethesda System of Reporting Thyroid Cytopathology” was introduced to resolve the problem of standardising terminology in Thyroid FNA diagnosis. This study aims to evaluate the histopathological correlation and to also assess the diagnostic accuracy of TBSRTC at an institutional level with respect to histopathology. Additionally, reclassification of these cases in accordance with new Update of WHO Classification of Thyroid tumors 2022.This is a 3-year retrospective study of thyroid lesions from August 2019 to August 2022 comprising of 160 cases. Data was retrieved from institutional database and analysed. Fine needle aspiration Cytology- Histopathological correlation followed by determination of diagnostic accuracy of TBSRTC was done using Sensitivity, Specificity, PPV, NPV and accuracy. Reclassification was done on the 160 histopathological diagnosis based on the new updated classification.Study showed female predominance and largest cohort belonged to the age group of 21–40 years. Cytohistopathological correlation was done and 4 discordant cases were identified. The Sensitivity, Specificity, PPV, NPV and Accuracy was found to be 95.77, 98.87, 98.55%, 96.7% and 97.5% respectively. On reclassification, the tumors were now classified based on cell of origin and maximum no. of cases were identified under the category of Follicular- cell derived.FNAC is a sensitive and specific method of evaluating thyroid lesions. TBSRTC shows excellent diagnostic accuracy in detecting malignant lesions and can be used for screening neoplasm. The new classification demonstrates classification based on tumour cell of origin. It is crucial for Clinicians and Pathologists to be informed of new terminologies and classification schemes to aid more therapeutic options for patients.