Purpose: We aimed to compare the diagnostic value of fine-needle aspiration cytology (FNAC) and fine-needle aspiration thyroglobulin measurements (FNA-Tg) for detecting cervical lymph node metastases from differentiated thyroid carcinomas.
Methods: This prospective study included 225 patients with neck node metastases or recurrences of papillary thyroid carcinoma. From the 225 patients, 255 lymph nodes were evaluated by FNAC and FNA-Tg. Final diagnoses confirmed by histological examination were compared to preoperative FNAC and FNA-Tg results.
Results: FNAC correctly diagnosed 212 metastatic lymph nodes but failed to diagnose 43 of them. FNA-Tg correctly diagnosed 253 metastatic lymph nodes but failed to diagnose two of them. FNA-Tg levels showed 100% sensitivity, 96% specificity, 99% diagnostic accuracy, a 99% positive predictive value (PPV) and a 100% negative predictive value (NPV) with a threshold level of FNA-Tg with a diagnostic accuracy 28.5 ng/ml. The specificity, diagnostic accuracy, PPV and NPV of FNA-Tg were significantly higher than those of FNAC.
Conclusion: FNA-Tg measurement can be performed safely for the detection of lymph node metastasis in patients with differentiated thyroid carcinomas.