Detection of Central Compartment Lymph Node Metastasis of Thyroid Cancer: Usefulness of Intraoperative Thyroglobulin Measurement in Fine Needle Aspiration Washout with and Without Blue Dye Injection
by
, , , , , , and
Chiara Mura
1,†
,
Gian Luigi Canu
2,†,
Giulia Lanzolla
1,*
,
Federico Cappellacci
2,
Fabio Medas
2
,
Stefano Mariotti
1,
Pietro Giorgio Calò
2
and
Francesco Boi
1 1
Endocrinology Unit, Department of Medical Sciences and Public Health, University of Cagliari, 09100 Cagliari, Italy
2
Surgery Unit, Department of Surgical Sciences, University of Cagliari, 09100 Cagliari, Italy
*
Author to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Cancers 2025, 17(3), 422; https://doi.org/10.3390/cancers17030422
Submission received: 28 December 2024
/
Revised: 23 January 2025
/
Accepted: 26 January 2025
/
Published: 27 January 2025
(This article belongs to the Special Issue Thyroid Cancer: New Advances from Diagnosis to Therapy: 2nd Edition)
Simple Summary
The early identification of metastatic lymph nodes in the central neck compartment (CNC) is crucial in tailoring the extent of the surgery in differentiated thyroid carcinoma. This prospective study explores the accuracy of intraoperative thyroglobulin measurement in the fine needle aspiration (Tg-FNA) of CNC lymph nodes to detect hidden metastases. We compared two methods: identifying lymph nodes using the blue dye technique versus the inspection and palpation of suspicious nodes. All lymph nodes selected were subjected to Tg-FNA and then histologically analyzed to identify metastases. Our findings revealed that the blue dye technique was unreliable. Intraoperative Tg-FNA without blue dye was reliable in detecting CNC metastases, although a higher Tg-FNA cutoff is needed in this compartment compared to what has been reported for lateral lymph nodes in the literature. Lymphatic drainage and surgical manipulation might explain these findings. With careful interpretation, intraoperative Tg-FNA can guide surgical decisions and avoid unnecessary CNC lymph node dissections.
Abstract
Background/Objectives: The management of lymph node metastases of the central neck compartment (CNC) in differentiated thyroid carcinoma is debated. The intraoperative measurement of thyroglobulin (Tg) has gained attention in accurately detecting metastases, reducing unnecessary CNC dissections. Methods: A total of 37 patients underwent surgery. An intraoperative assay of thyroglobulin from fine needle aspiration (Tg-FNA) was performed on CNC lymph nodes, identified by blue dye injection in 15 patients (23 nodes, group A) and by palpation in 22 patients (35 nodes, group B). The Tg-FNA values were compared with histology to calculate the diagnostic accuracy. Results: In group A, the blue dye diffused widely, complicating lymph node identification: 2 were metastatic and 21 non-metastatic, with median Tg-FNA levels of 6236 ng/mL and 99.20 ng/mL, respectively. In group B, 8 were metastatic and 27 benign, with median Tg-FNA levels of 4063 ng/mL and 121 ng/mL (p < 0.0001), respectively. ROC analysis identified 500 ng/mL as a cutoff, achieving 100% sensitivity and 74% specificity in group B and 90% sensitivity and 70% specificity overall. Finally, among the non-metastatic lymph nodes, group A exhibited some cases of very high Tg-FNA values compared to group B, with lower accuracy for the cutoff, suggesting that colorant injection might lead to increased Tg-FNA levels. Conclusions: Blue dye injection showed low accuracy. Intraoperative Tg-FNA was reliable in detecting CNC metastases, although a higher cutoff is needed in this compartment compared to what has been reported for lateral lymph nodes. Lymphatic drainage and surgical manipulation might explain these findings. The careful interpretation of Tg-FNA in CNC should be adopted.
