Classification of thyroid fine-needle aspiration cytology into Bethesda categories: An institutional experience and review of the literature

Background: Fine-needle aspiration cytology (FNAC) of thyroid is the initial screening test for thyroid nodules. The Bethesda system classifies thyroid FNAC into six categories. Each category is linked to a malignancy risk and has a recommended clinical management. The aim of this study is to analyze the thyroid cytology smears by Bethesda system and to correlate the diagnosis of cytopathology with histopathology, whenever surgery was done. Materials and Methods: This study presents our experience with the Bethesda system in 681 thyroid FNAs from 632 patients in the period between January 2013 and December 2016. Results: Categories were as follows: 10.1% were Category I (nondiagnostic), 68.8% Category II (benign), 12.4% were Category III (atypia of undetermined significance), 2.9% were Category IV (suspicious for follicular neoplasm), 2.6% were Category V (suspicious for malignancy), and 4.1% were Category VI (malignant). Surgery was done on 126 nodules from 119 patients with an overall rate of malignancy of 27.8% (35/126 nodules). Conclusion: The Bethesda System for Reporting Thyroid Cytopathology proved to be an excellent reporting system.