The false-negative rate of fine-needle aspiration cytology for diagnosing thyroid carcinoma in thyroid nodules

Purpose Our aim was to define the false-negative rate of fine-needle aspiration cytology (FNAC) for diagnosing thyroid carcinoma in thyroid nodules <4 cm versus >= 4 cm. Materials and methods Six hundred sixty-two patients with thyroid nodules who underwent FNAC and surgery at our institution were analyzed. The association of predictive factors with thyroid carcinoma was evaluated. The sensitivity, specificity, and the false-negative rate of FNAC were calculated. Results The incidence of thyroid carcinoma was significantly higher in nodules >= 4 cm (24%) compared with nodules <4 cm (12%). The false-negative rates of FNAC were 2% in all nodules and 1.3% and 4.3% in nodules <4 cm and >= 4 cm (p=0.9), respectively. Sensitivity and specificity of FNAC were 90% and 79%, respectively. Conclusions The false-negative rate of FNAC is low for thyroid nodules <4 cm and for nodules >= 4 cm.