Diagnostic Performance of Thyroglobulin Value in Indeterminate Range in Fine Needle Aspiration Washout Fluid from Lymph Nodes of Thyroid Cancer

Abstract

PurposeThe purpose was to compare the frequency of metastatic and nonmetastatic lymph nodes diagnosed by fine needle aspiration biopsy cytology (FNAC) and thyroglobulin concentration from fine needle aspiration biopsy washout fluid (FNAB-Tg) in an indeterminate range (0.2-100 ng/mL), and to evaluate the most appropriate threshold value of FNAB-Tg in an indeterminate range.Materials and MethodsWe performed ultrasound-guided FNAB and FNAB-Tg in suspicious metastatic cervical lymph nodes of papillary thyroid carcinoma and performed surgery. Ninety-five lymph nodes with indeterminate values of FNAB-Tg ranging from 0.2-100 ng/mL in ninety-two patients were included in this study. The diagnostic performances in multiple Tg levels (0.7, 1.0, 5.0, 10.0, 20.0, 50.0) were evaluated to compare with FNAB cytology using sensitivity, specificity, and accuracy with area under the curve (AUC) analysis.ResultsForty-two were metastatic lymph nodes and fifty three were nonmetastatic lymph nodes. FNAB-Tg ranged from 0.22 to 90.9 ng/mL in metastatic lymph nodes (mean; 34.3±33.3 ng/mL) and 0.20 to 56.7 ng/mL in nonmetastatic lymph nodes (mean; 4.9±11.1 ng/mL) (p<0.001). The most excellent diagnostic performance was displayed in 5 ng/mL of FNAB-Tg with AUC of 0.76, sensitivity, specificity, accuracy, 69.0, 83.0, and 76.8, respectively. However, there was no significant difference from 10 ng/mL FNAB.ConclusionWe ascertained that 5 ng/mL yielded the most excellent diagnostic performance among FNAB-Tg levels in the present setting with a large series with the indeterminate range (0.2-100 ng/mL) of FNAB-Tg values. These results need additional confirmation under different laboratory conditions.

Optimized Cutoff Value and Indication for Washout Thyroglobulin Level According to Ultrasound Findings in Patients with Well-Differentiated Thyroid Cancer

“…13 The result of our study, 1.8 ng/mL, was between the 2 reports. Moreover, we demonstrate that the value of FNA-Tg was not useful in nodes without suggested suspicious US findings (Fig 3).…”

Lowered cutoff of lymph node fine-needle aspiration thyroglobulin in thyroid cancer patients with serum anti-thyroglobulin antibody

“…Several studies were conducted on preoperative patients (7,13,23,24,25) but the small number of cases precluded any strong conclusion and the TgAb status was not considered. Prior studies also showed the effect of TgAb status on FNA-Tg levels but did not consider the operative status (5,10,26).…”

“…When LNs were suspicious for malignancy in ultrasonography but cytology results revealed benign LNs, LN dissection and histopathologic confirmation were performed if there were malignant LNs in the same compartment (7,13). Otherwise, decreased or same-size LNs in follow-up ultrasound after 6-12 months were defined as benign in the final outcome (21).…”

Measurement of thyroglobulin, calcitonin, and PTH in FNA washout fluids

“…Relevant differences between these two studies are observed in Tg assays and samples management. All in all, both sensitivity and specificity of FNA-Tg was higher in surgically treated DTC than in those waiting for surgery [32,33] and, consequently, this suggests to combine cytology with FNA-Tg. A cutoff level obtained by "high-sensitivity" assays should provide more accurate data.…”