Clinical impact of thyroglobulin (Tg) and Tg autoantibody (TgAb) measurements in needle washouts of neck lymph node biopsies in the management of patients with papillary thyroid carcinoma

Abstract

Objectives:The presence of thyroglobulin (Tg) in needle washouts of fine needle aspiration biopsy (Tg-FNAB) in neck lymph nodes (LNs) suspected of metastasis has become a cornerstone in the followup of patients with papillary thyroid carcinoma (PTC). However, there are limited data regarding the measurement of anti-Tg antibodies in these washouts (TgAb-FNAB), and it is not clear whether these antibodies interfere with the assessment of Tg-FNAB or whether there are other factors that would more consistently justify the finding of low Tg-FNAB in metastatic LNs. Materials and methods: We investigated 232 FNAB samples obtained from suspicious neck LNs of 144 PTC patients. These samples were divided according to the patient's serum TgAb status: sTgAb-(n = 203 samples) and sTgAb+ (n = 29). The TgAb-FNAB levels were measured using two different assays. Tg-FNAB was also measured using two assays when low levels (< 10 ng/mL) were identified in the first assay of the metastatic LNs from the sTgAb+ samples. Results: The TgAb-FNAB results were negative in both assays in all samples. Low levels of Tg-FNAB were identified in 11/16 of the metastatic LNs of the sTgAb+ patients and 16/63 of the sTgAb-patients (p < 0.05) using assay 1. The measurement of the Tg-FNAB levels using assay 2 indicated additional metastases in 5 LNs of the sTgAb+ patients. Conclusions: Factors other than the presence of TgAb-FNAB may contribute to the higher number of metastatic LNs with undetectable Tg-FNAB in the sTgAb+ group. In addition, the measurement of Tg-FNAB using different assays was useful to enhance the diagnosis of metastatic LNs, particularly when cytological and Tg-FNAB results are discordant.

CYFRA 21-1 in Lymph Node Fine Needle Aspiration Washout Improves Diagnostic Accuracy for Metastatic Lymph Nodes of Differentiated Thyroid Cancer

“…The measurement of FNA washout Tg in thyroid cancer was proposed in 1992 by Pacini et al [10], as a supplementary tool to FNAC for the detection of cervical LNs metastases. Several studies have reported that washout Tg was more sensitive than FNAC for detecting metastases and that the sensitivity of FNAC improved after combination with washout Tg [5,20,21,22,23]. The sensitivity (92.9%) of washout Tg was higher than that of FNAC alone (85.7%) and sensitivity was increased from 85.7% to 88.1% when combined with washout Tg.…”

Thyroglobulin Measurement in Needle Aspiration for Detection of Recurrences and Neck Metastases in Patients with Differentiated Thyroid Carcinoma: Significance of Anti-Tg Antibodies

“…While it is known that serum TgAb interferes with serum Tg measurement, producing underestimation of Tg concentration, some previous studies have shown that FNA-Tg measurement is valid in patients with circulating serum Tg-Ab ( 9 , 16 , 20 , 32 , 34 , 37 , 39 ). A possible explanation was that intracellular Tg was not exposed to circulating sTgAb, but these results have not been confirmed in all studies ( 16 ).…”

“…The limitations of statistical analysis consisted in significantly elevated values of Tg in certain samples because no further sample dilution was performed. High FNA-Tg values over 2000 ng/mL can lead to false-elevated FNA-TgAb ( 39 , 45 ). The limitation of our study design was that we did not have enough histological data for further comparison with cytology and FNA-Tg results.…”

Diagnostic role of FNA cytology in the evaluation of cervical lymph nodes in thyroid cancers: Combined evaluation of thyroglobulin in eluate from FNA cytology

“…Their results confirmed that the presence of TgAb‐FNAB might contribute to the identification of metastatic lymph nodes when there is undetectable Tg‐FNAB and FNAC is controversial. Furthermore, the use of different assays might be useful to increase the number of doubtful cases with cytological and Tg‐FNAB discordant results 22 . In an article by Deacu et al., the authors retrospectively evaluated all Tg‐FNAC measurements and compared them with both FNAC results and pathology reports.…”