The role of ultrasound in thyroid nodules with a cytology reading of "suspicious for papillary thyroid carcinoma"

Background: Irrespective of ultrasound (US) features, surgery is usually recommended for patients who have a fine-needle aspiration biopsy (FNAB) read as suspicious for papillary carcinoma (PTC). The aim of the present study was to evaluate the role of US in the management of thyroid nodules with a FNAB reading suspicious for PTC. Methods: Between August 2002 and May 2006, 303 patients who had thyroid nodules with a FNAB reading suspicious for PTC underwent surgery. The sonographic findings in the patients were classified as suspicious for malignancy or probably benign based on the US reading. The US readings and final pathological diagnoses of thyroid nodules were analyzed in these patients. Results: The malignancy rate was 84.2% in patients with a FNAB specimen suspicious for PTC. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of the US were 96.4%, 74.5%, 92.7%, 94.9%, and 80.9%, respectively, in nodules read as suspicious for PTC on FNAB. Whereas 243 (96.4%) lesions were found to be malignant at surgery, in the 252 lesions that had ultrasound findings suspicious for malignancy, only 13 (25.5%) lesions were malignant out of the 51 that had US readings of probably benign (p < 0.05). Conclusions: The probability of malignancy is much lower in thyroid nodules with benign US findings even if the FNAB is read as suspicious for PTC. Therefore, US may be useful in planning the extent of surgery in patients with a FNAB reading of suspicious for PTC. As thyroid malignancy occurs in approximately 26% of patients with cytology readings suspicious for PTC and benign-appearing US, the US reading alone is not sufficient to determine the need for surgery. The US and FNAB are complementary to each other and should be useful when providing informed consent before thyroid surgery.