[Fine-needle aspiration for the diagnosis of lymph node metastasis in papillary thyroid carcinoma]

Objective: To investigate the diagnostic performance of fine-needle aspiration (FNA) cytology for the detection of lateral lymph node metastases in patients with papillary thyroid carcinoma (PTC). Methods: A total of 109 lateral lymph nodes with suspicious metastases from 85 patients were retrospectively subjected to FNAC, fine-needle aspiration thyroglobulin measurement (FNATg), and FNATg/SerumTg measurement. Lymph node pathological results after surgery were taken as the gold standard. Using Mann-Whitney U test, Pearson linear model and ROC curve were used for data analysis. Results: The sensitivity, specificity and accuracy of FNATg for the diagnosis of lateral neck lymph node metastasis were respectively 93.7%, 90.0% and 93.3% and those of FNATg/SerumTg were respectively 89.9%, 90.0% and 93.2% respectively, the threshold values for FNATg and FNATg/SerumTg were 0.925 ng/ml and 1.007, respectively. The sensitivity, specificity and accuracy of FNATg combined with FNAC were respectively 91.0%,93.5% and 94.4%. The existence of thyroid tissue and the expression of serum Tg did not affect the expression of lymph node FNATg. The FNATg cutoff value of 0.925 ng/ml showed the best diagnostic performance in patients with a thyroid gland, while the FNATg/SerumTg cutoff ratio of 14.95 showed the best diagnostic performance in patients without a thyroid gland. The serum TgAb significantly interfered with the expression of FNATg in the lateral neck metastatic lymph nodes (P=0.049). Conclusions: FNATg alone or the combination of FNATg with FNAC are highly reliable in the diagnosis of lateral neck lymph node metastases in patients with PTC. The expression of TgAb may interfere with the accuracy of the diagnostic performance of FNATg.