Impact of preoperative ultrasonographic staging of the neck in papillary thyroid carcinoma.

OBJECTIVE To determine the frequency of occult macroscopic metastasis detected by preoperative US evaluation of the neck in patients with PTC. Papillary thyroid carcinoma (PTC) is a malignancy with a high rate of lymph node metastasis. The findings of routine thyroid ultrasonography (US) and physical examination may underestimate metastatic disease. Thus, we propose that patients diagnosed as having PTC undergo preoperative US staging of the neck. DESIGN This prospective study included 60 patients diagnosed as having PTC from January 1 through June 30, 2006. Patients had undergone previous thyroid US evaluation with no palpable adenopathy. Lymph nodes were deemed suspicious by US findings with a minor axis greater than 10 mm, a minor axis greater than 50% of the major axis, or hyperechogenicity with or without microcalcifications. Metastasis was confirmed by fine-needle aspiration biopsy or frozen section analysis. Patients with confirmed metastasis underwent a neck dissection. The location of adenopathy reported by US was correlated with the pathological report. RESULTS The US evaluation identified 12 of 60 patients (20%) with adenopathy suggestive of metastasis. Metastasis was confirmed in 11 of 12 patients (92%). Metastasis was found in 1 of 48 patients who had a negative US finding. Overall, sensitivity, specificity, and positive and negative predictive values were 92%, 98%, 92%, and 98%, respectively. All neck levels with suspicious adenopathy detected by US evaluation, with 1 exception, were confirmed by pathological findings. Nine patients had additional neck levels involved with microscopic disease undetected by the US evaluation. CONCLUSIONS In patients with PTC, preoperative US evaluation of the neck is effective in detecting nonpalpable metastasis. Therefore, routine preoperative neck US evaluation is recommended to optimize primary surgical planning.