Estimation of thyroglobulin in lymph node aspirates: Pilot experience from a tertiary referral cancer center

Abstract

Background: Assessment of cervical lymph node involvement in patients with thyroid cancer either during preoperative surgical mapping or detection of recurrences during follow-up is a crucial step in the management of differentiated thyroid cancers (DTCs). In most patients, fine needle aspiration cytology (FNAC) confirms the presence of metastasis in lymph node. However, in cases of paucicellular lymph node aspirate or discordant sonogram and cytology results, thyroglobulin (Tg) measurement in the lymph node aspirate (FNA-Tg) is useful and a value >1 ng/ml is considered consistent with metastatic disease. Context: The addition of FNAC to the US improves the specificity, but 5-10% are nondiagnostic and 6-8% rate of false-negative results. Several studies have reported that the detection of Tg in FNA-needle washes improves the evaluation of suspicious lymph nodes in patients with DTC.Data from Indian centers on FNA-Tg are limited. Aims: We piloted the utility of FNA-Tg in patients with sonographically suspicious cervical lymph node enlargement in the setting of suspicious thyroid nodule or in the follow-up of thyroid cancer. Settings and Design: Prospective data collection. Results: We measured Tg in 13 lymph node aspirates (12 patients, 10 females) among whom 4 patients had a total thyroidectomy and 1 had a hemithyroidectomy. Eight of the 13 lymph node aspirates had FNA-Tg values >150 ng/ml, all of them had unequivocal malignant cytology and four among them had proven metastatic DTC on surgical pathology. The median FNA-Tg of the patients with malignant cytology was 7550 ng/ml with a range of 162-30,000 ng/ml. Among the remaining 5 lymph node aspirate, 2 lymph nodes showed cytological features suggestive of reactive lymphadenitis (FNA-Tg < 0.2 ng/ml) and were not operated, 1 had a high-grade malignancy consistent with anaplastic thyroid cancer (FNA-Tg < 0.2 ng/ml), and 2 had nondiagnostic cytology (one had non-caseating granuloma on surgical pathology [FNA-Tg 1.3 ng/ml] and in the other patient [FNA-Tg < 0.2 ng/ml] surgical intervention was deferred). Conclusions: FNA-Tg was concordant with positive cytology in all patients with DTC and may serve as a useful tool in patients with negative and nondiagnostic cytology to guide surgical management.