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

This large multicentre study validates the EASL/AASLD recommendations in daily practice. Specificity using CT or MRI in 10-20 mm HCC was low, but we do not recommend combined imaging at first as sensitivity would be very low. The best sequential approach combined MRI and CEUS.