Significance of low levels of thyroglobulin in fine needle aspirates from cervical lymph nodes of patients with a history of differentiated thyroid cancer

Abstract

Objective: Measurement of thyroglobulin in the washout of lymph node (LN) fine needle aspirates is recommended in the follow-up of patients with differentiated thyroid cancer (DTC). The significance of low fine needle aspirates thyroglobin (FNATg) levels remains a question, which we addressed. Method: Prospective study comparing FNATg with FNA cytology. Exploration of 34 DTC patients (53 cervical LNs), 26 non-thyroidectomized patients with a thyroid-unrelated cervical mass (negative controls) and 13 with 21 thyroid nodules (positive controls). The 12 DTC patients (19 LNs) with a malignant FNA cytology and/or high FNATg level received LN surgery (11 patients) or I 131 -iodine treatment (1 patient) and the outcome measure was pathological or scintigraphic evidence of DTC LN metastasis. Results: All 26 negative controls showed FNATg !1 ng/FNA and all 21 positive controls showed high levels of FNATg (127-210 000 ng/FNA, median 38 000). Among DTC patients in 25 LNs with a benign FNA cytology, FNATg was undetectable in 24 and low in 1 (6 ng/FNA); in 19 LNs with a malignant FNA cytology, FNATg was high in 17 (80-140 000 ng/FNA, median 7174 ng/FNA) and low in 2 (6.6 and 7.1 ng/FNA), which proved to be low Tg immunostaining oncocytic DTC metastasis; in 9 LNs with a noninformative cytology, FNATg was undetectable in 8 but 11 825 ng/FNA in 1, which proved a DTC metastasis. Measurement of FNA albumin demonstrated that contamination of FNA by serum proteins was negligible. Conclusion: Low FNATg levels can indicate a DTC metastasis. It cannot be related to clinically relevant levels of serum Tg.European Journal of Endocrinology 158 691-698

Thyroglobulin measurements in washout of fine needle aspirates in cervical lymph nodes for detection of papillary thyroid cancer metastases

“…in a cervical mass is related to the presence of thyroid cells. Nevertheless, low levels of FNAB-Tg have been observed in control patients (7,13) and can be explained by presence of 'matrix effects' artifacts depending on the antibodies and medium used (21). To further support this hypothesis, we demonstrated here that the FNAB-Tg level does not change according to the serum TSH in patients without LN disease.…”

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

“…We used the value of 10 ng/mL, which is consistent with the majority of published reports (11,14,(20)(21)(22).…”

“…Following the inclusion of a limited number of TgAb-FNAB measurements of LN washout in sTgAb+ patients, the authors did not detect TgAb via direct measurement in the washout fluids of LNs, which suggests that sTgAb do not interfere with the detection of Tg-FNAB levels (16,18,20,26).…”

“…These results may occur in cases of small or cystic LN metastases, which reflect a lack of tumor cells detected during the FNAB procedure (11). Nevertheless, the use of Tg-FNAB alone has several limitations, and despite being well established as an important tool in the investigation of suspicious LN metastases, Tg-FNAB presents variable results between metastatic and non-metastatic LNs (3,4,(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23). This subject has been the topic of recent reviews and meta-analysis studies (12,13).…”

“…It remains controversial whether these antibodies also interfere with the assessment of TgAb-FNAB. Previous studies on this topic have included a limited number of patients with positive serum antiTg antibodies (sTgAb+) (25)(26)(27) and limited direct measurements of TgAb-FNAB (16,18,20,25,26).…”