Ultrasound-guided fine-needle aspiration of thyroid nodules: does the size limit its efficiency?

PURPOSE The management criterion of thyroid nodules is to evaluate the risk of malignancy, based on cytological examinations. Ultrasound-guided fine-needle aspiration biopsy (US-FNAB) has a highly diagnostic value for thyroid nodules. The aim of this study was to compare the efficacy of US-FNAB for thyroid nodules with different sizes. MATERIAL AND METHODS From August 2013 to November 2013, 344patients with thyroid nodules who had undergone US-FNAB were divided into three groups, according to the largest diameter of their nodules (group A, ≤5.0 mm; group B, 5.1-10.0 mm; group C, >10.0 mm). All the nodules were subsequently verified by histology or follow-up findings. The accuracy, sensitivity, specificity, positive predictive value, negative predictive value of aspiration cytology in each group was compared. RESULTS Among 344 thyroid nodules diagnosed by cytology, the cytology was classified as nondiagnostic or unsatisfactory for 53 (15.4%) lesions, benign for 144 (41.9%) lesions, atypia of undetermined significance or follicular lesion of undetermined significance for 20 (5.8%) lesions, follicular neoplasm or suspicious for a follicular neoplasm for 26 (7.6%) lesions, suspicious for malignancy for 36 (10.5%) lesions, malignant for 65 (18.9%) lesions. There were 243 benign and 101 malignant nodules confirmed by the pathological or follow-up ultrasound. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were confirmed to be 87.5% (14/16), 92.5% (37/40), 91% (51/56), 82.3% (14/17), and 94.8% (37/39) in group A; 92.3% (36/39), 96.9% (94/97), 95.5% (130/136), 92.3% (36/39), and 96.9% (94/97) in group B; and 91.3% (42/46), 93.4% (99/106), 92.7% (141/152) 85.7% (42/49), and 96.1% (99/103), in group C. There were no statistical differences in accuracy, sensitivity, specificity, false positive accuracy, false negative rate of fine needle aspiration of thyroid nodules with different sizes (P>0.05). CONCLUSION US-FNAB has similar diagnostic efficacy to thyroid nodules with different sizes.