Abstract

AIMS AND OBJECTIVES: The aim of the study is to examine the adequacy and accuracy of ultrasound-guided fine-needle aspiration cytology (US-FNAC) in thyroid nodules ≥1 cm and to analyze the clinical, sonological, and cytological features in predicting thyroid malignancy.

MATERIALS AND METHODS: US-FNAC was done on 290 patients from December 2013 to December 2014 by the radiologist. The Thyroid Imaging Reporting and Data System (TIRADS) was used to record the sonological features. FNAC samples were reported by a dedicated cytopathologist. Accuracy was calculated by comparing US-FNAC, clinical features and ultrasound (US) features for those who had final histopathology till April 2017.

RESULTS: The adequacy of US-FNAC in this study was 80.2%. Thyroidectomy was performed in 128/290 (44.1%). The sensitivity and specificity of US-FNAC in this study is 83.9 and 76.3%, respectively, with a positive predictive value of 85.2%, negative predictive value of 74.4%, and an accuracy of 81% in predicting malignancy in thyroid nodules ≥1 cm. The malignancy rate in benign FNAC sample was 25% (10/40), and was 69% (8/13) in those with a follicular lesion of undetermined significance (FLUS). Around 80% of benign and 89% of FLUS had follicular variant of papillary carcinoma of thyroid (FVPTC). US-FNAC, a high TIRADS score, and US features such as marked hypoechogenicity, taller than wide, irregular margins, microcalcification, and clinical features, such as hard in consistency and significant cervical lymph nodes, were important in predicting malignancy ( < 0.001).

CONCLUSIONS: The accuracy of US-FNAC in this study is 81%. The US-FNAC, a high TIRADS score, a hard thyroid nodule, and significant cervical lymph nodes are important in predicting malignancy. The accuracy rate in benign and atypia undetermined significance categories needs to improve in this study. Further research to help in decreasing false negative rates of FVPTC will help in increasing the accuracy of US-FNAC in the present study.