Thyroglobulin Measurement in the Fine-Needle Aspiration Washout for Diagnosing Cervical Lymph Node Metastasis in the Patients with Differentiated Papillary Thyroid Cancer

Abstract

Purpose: We wanted to evaluate the utility of thyroglobulin measurement in the washout of the needle (FNATg) used for fine needle biopsy for detecting lymph node metastasis in patients with differentiated papillary thyroid carcinoma (DPTC). Materials and Methods: We performed ultrasonography-guided fine-needle aspiration cytology (FNAC) and FNA-Tg for 50 ultrasonographically suspicious lymph nodes in 45 DPTC patients. Eighteen patients underwent thyroidectomy before FNA and the remaining 27 patients underwent fine-needle aspiration prior to surgery. The final diagnoses were determined based on the results of histological examination of the excised specimens (n=21) or on the follow-up examination that was done least 12 months after surgery. Results: Lymph node metastases were confirmed in 19 patients. FNAC detected 14 metastatic lymph nodes in 14 patients, and FNA-Tg detected 18 metastatic lymph nodes in 18 patients. While none of 3 cystic lymph nodes metastasis was detected via FNAC, they all revealed positive results via FNA-Tg. One patient with a negative result on both methods had one metastatic lymph node among 9 excised lymph nodes, and this one node had not been sampled via FNAC or FNA-Tg. The sensitivities and specificities of FNAC and FNA-Tg were 73.6% (14/19) and 100% (27/27), and 94.7% (18/19) and 96.2% (26/27), respectively. Conclusion: FNA-Tg is a useful technique for the early detection of lymph node metastasis, and especially for detecting cystic lymph node metastasis in patients with DPTC.