Added value of thyroglobulin measurement in the fine-needle aspiration washout to diagnose cervical metastatic lymphadenopathy from papillary thyroid cancer

The aim of this study was to evaluate added value and diagnostic threshold value of thyroglobulin measurement in the fine-needle aspiration washout for detecting cervical lymph node metastasis from papillary thyroid cancer on pre and postoperative patients. Total 219 cervical lymph nodes from 180 patients with papillary thyroid cancer were evaluated for fine needle aspiration cytology and thyroglobulin in fine needle aspiration (FNA-Tg), using immunometric chemiluminescent assay. Eighty-six patients were preoperative and remaining 94 patients were on follow up after total thyroidectomy. Final diagnoses were made on pathology of dissected lymph nodes or follow-up examination for at least 12 months. One hundred and twelve metastatic lymph nodes were finally confirmed in 94 patients out of total 180 patients. Sensitivity of FNA-Tg was 99.1, 98.21, 97.20%, respectively with threshold level at 1, 10, serum Tgng/mL, which were higher sensitivity of fine needle aspiration. Combined FNA and FNA-Tg with threshold at 1, 10, 100 ng/mL raised sensitivity and specificity to 100%, respectively. All 6 lymph nodes that were false negative on FNA were correctly diagnosed as metastasis on FNA-Tg with threshold of 1, 10, 100, and serum thyroglobulin. FNA-Tg with threshold level at 100 ng/mL combined FNA showed highest sensitivity (100%) and specificity (97.56%) on preoperative patient groups among the 1, 10, 100, serum Tg threshold value. But, FNA only showed adequately high sensitivity (100%) and specificity (96.96%) on postoperative patient groups. Using receiver operating characteristic curve (ROC) curve analysis, cut off value was 57.69 in total patient, 78.66 in preoperative patient, and 32.81 in postoperative patient. FNA-Tg combined with FNA showed excellent sensitivity and specificity. FNA-Tg showed very high sensitivity and specificity at threshold level 78.66 ng/mL in preoperative patients, but FNA-Tg had less benefit on the postoperative patient group, having high sensitivity and specificity with FNA alone