Thyroglobulin concentration measurement in fine-needle aspiration fluid from cystic cervical lymph node metastases of papillary thyroid carcinoma

Background: Combining ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI) and fine-needle aspiration cytology (FNAC) usually results in the best preoperative diagnosis of cervical masses, including neoplasms. This may not be tnie, however, especially in occult papillary thyroid carcinoma (PTC) associated with single cystic cervical lymph node metastasis. We assessed the role of thyroglobulin measurement in FNA fluid (FNATg) in differentially diagnosing cystic cervical mass lesions, including PTC cystic lymph node metastasis. Methods: We reviewed the records of 17 subjects with cervical cystic masses undergoing both FNATg measure ment and surgery. FNA was done under ultrasonographic guidance. We also measured FNATg concentrations from extrathyroid lesions, consisting of cystic cervical lymph node metastases and benign cystic lesions. Results: Pathological diagnosis involved 5 PTC lymph node metastases, 3 lateral cervical cysts, 7 thyroglossal duct cysts, and 2 squamous cell carcinoma (lung and oropharynx) lymph node metastases. FNATg of PTC lymph node metastasis was much higher than the reference range of blood serum thyroglobulin, although much lower for the lateral cervical cyst detection threshold. FNAC and FNATg measurement are thought to be mutually complementary in the differential-diagnosis of PTC cystic lymph node metastasis. Conclusion : High concentrations of FNATg in a cystic cervical mass is considered specific to PTC lymph node metastasis, indicating its usefulness in distinguish PTC cystic metastasis from other cystic lesions. Including FNATg measurement with FNAC may thus improve preoperative diagnosis accuracy without additionally stressing subjects with PTC cystic lymph node metastasis.