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Objective: Fine-needle aspiration cytology (FNAC) is the principal method for evaluating thyroid nodules. Currently, the reporting hereof is based on the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC), which classifies lesions into six diagnostic categories, each with its own malignancy risk and management guidelines. In this study, we aimed to assess the accuracy of FNAC performed in our institution.
Methods: A retrospective study was executed to compare the cytology and histopathology results for patients undergoing both thyroid FNAC and subsequent thyroid surgery between 2013 and 2020. Cytological diagnoses were classified according to the 2017 TBSRTC.
Results: The incidence of the cytological categories in the 131 FNAC samples were as follows: Nondiagnostic 11.5%; benign 19.8%; atypia/follicular lesion of undetermined significance 6.9%; (suspicious for) a follicular neoplasm 28.2%; suspicious for malignancy 13.7%; and malignant 19.8%. Final pathology showed malignancy rates of 13.33%, 7.69%, 33.33%, 13.51%, 83.33%, and 100.00% for each Bethesda category I to VI respectively. The sensitivity, specificity, positive and negative predictive value and diagnostic accuracy were 91.67%, 40.68%, 56.79%, 92.31%, and 62.62% respectively.
Conclusion: The malignancy rates of thyroid nodules examined with FNAC at our institution were higher than the rates reported in the Bethesda system for all categories, except category IV and VI. The wide variability in calculation of thyroid FNAC statistics makes comparison difficult and highlights the need for uniform definitions. We strongly support further investigation in this field as our findings warrant the need for institution-specific data to ameliorate the management of thyroid nodules.
Cite this article as: Deschuytere L, Cools G, De Schepper S, Van Bruaene N. Cytology versus histopathology in thyroid nodules: a retrospective study. B-ENT 2021; 17(2): 92-7.