Intraoperative measurement of thyroglobulin in lymph node aspirates for the detection of metastatic papillary thyroid carcinoma

BACKGROUND Among patients with papillary thyroid carcinoma (PTC), 30%-80% have cervical lymph node (LN) metastases, which are most commonly located in the central compartment. However, preoperative ultrasonography identifies malignant central compartment LNs in only 20%-30% of cases. We aimed to evaluate the diagnostic value of intraoperative thyroglobulin (Tg) measurement in fine-needle aspirates (FNA-Tg) of suspicious metastatic LNs. METHODS In total, 75 patients (75 LNs) with PTC or suspected PTC were enrolled in this study. Suspicious metastatic LNs were isolated intraoperatively, and FNA-Tg was performed. Then, the Tg values were compared with the corresponding pathological results and preoperative ultrasonography. RESULTS In total, 37 LNs were diagnosed as malignant, and 38 were benign. According to the receiver operating characteristic (ROC) curve, the optimal cutoff value of intraoperative FNA-Tg was 147.5 ng/mL (sensitivity, 81.1%; specificity, 100%; p=0.000). The sensitivity and specificity for detecting central compartment LN metastasis were 77.78% (21/27) and 100% (36/36), respectively. The corresponding sensitivity of preoperative ultrasonography was lower than that of FNA-Tg (p=0.000). Serum Tg-antibody (Ab), thyroid-stimulating hormone (TSH) and thyroid peroxidase antibody (TPO-Ab) were not significantly associated with FNA-Tg values. There was no statistical correlation between preoperative serum Tg and intraoperative FNA-Tg (p=0.451). CONCLUSION Intraoperative FNA-Tg levels of suspicious metastatic cervical LNs can be useful for diagnosing metastatic PTC. Intraoperative LN-FNA-Tg may have an important role in determining which surgical procedure to perform.