- Recommendation #7 from ATA 2025 Guidelines:
- Preoperative neck ultrasound to evaluate cervical lymph nodes in the central and lateral neck compartments as well as for gross extrathyroidal extension is recommended for all patients undergoing surgery for malignant cytologic or molecular findings:
- Strong recommendation, Moderate certainty evidence
- Ultrasound-guided FNA of sonographically suspicious lymph nodes greater than 8 to 10 mm in the smallest diameter should be performed to confirm malignancy if this would change management:
- Strong recommendation, Moderate certainty evidence
- The addition of FNA-Tg washout in the evaluation of suspicious cervical lymph nodes may be performed in select preoperative patients, but interpretation may be dif cult in patients with an intact thyroid gland:
- Conditional recommendation, Low
certainty evidence
- Conditional recommendation, Low
- Preoperative neck ultrasound to evaluate cervical lymph nodes in the central and lateral neck compartments as well as for gross extrathyroidal extension is recommended for all patients undergoing surgery for malignant cytologic or molecular findings:
- Differentiated thyroid cancer (DTC), and particularly PTC:
- Involves cervical lymph nodes in 20% to 50% of patients in most series using standard
pathological techniques:- These metastases may be present even when the primary tumor is small and intrathyroidal
- The frequency of micrometastases (less than 2 mm) may approach 90%, depending on the sensitivity of the detection method:
- However, the clinical implications
of micrometastases are likely less significant compared with macrometastases:- They do not appear to affect survival when they are in the central neck
- They also do not appear to increase recurrence
- However, the clinical implications
- Involves cervical lymph nodes in 20% to 50% of patients in most series using standard
- Preoperative ultrasound identifies suspicious cervical adenopathy in:
- 20% to 31% of cases:
- Potentially altering the surgical approach:
- In as many as 20% of patients
- Potentially altering the surgical approach:
- It has significantly less clinical utility in identifying central neck lymph nodes:
- Due to the presence of the overlying thyroid gland
- 20% to 31% of cases:
- Sonographic features suggestive of abnormal metastatic lymph nodes include:
- Enlargement
- Loss of the fatty hilum (odds ratio [OR] 1.9)
- A rounded rather than oval shape:
- Long axis / short axis ≤ 2; OR 1.6
- Hyperechogenicity (OR 5.4)
- Cystic change (OR 71.8)
- Calcifications (OR 6.2)
- Peripheral vascularity or abnormal blood flow (OR 3.8)
- No single sonographic feature has adequate sensitivity for detecting lymph nodes with metastatic thyroid cancer; however:
- Cystic change:
- Has the highest odds of malignancy
- Absence of a fatty hilum, cystic changes, microcalcifications, abnormal vascularity, and cortical hyperechogenicity are all independent features of metastatic lymph nodes:
- With a high specificity of 87% to 99.6%
- Absence of a fatty hilum has the highest sensi-
tivity but low specificity at 66.4%
- Cystic change:
- The location of the lymph nodes also may be useful for decision-making:
- Metastatic lymph nodes are much more likely to occur in Levels III, IV, and VI than in Level II:
- Although this may not be true for PTC tumors arising in the upper pole of the thyroid:
- Which have a higher propensity to produce skip metastases to Levels II and III
- Although this may not be true for PTC tumors arising in the upper pole of the thyroid:
- Metastatic lymph nodes are much more likely to occur in Levels III, IV, and VI than in Level II:
- Confirmation of malignancy in lymph nodes
with a suspicious sonographic appearance:- Is achieved by ultrasound-guided FNA aspiration for cytology and / or measurement of Tg in the needle washout (FNA-Tg):
- Tg washout is a helpful adjunct to FNA:
- Particularly in cases where the lymph nodes are cystic, cytological evaluation of the lymph node is inadequate, or the cytological and sonographic evaluations disagree:
- Example – normal cytological biopsy of a large lymph node with microcalcifications
- Particularly in cases where the lymph nodes are cystic, cytological evaluation of the lymph node is inadequate, or the cytological and sonographic evaluations disagree:
- False positive Tg washout may occur:
- Particularly in lymph nodes in the central compartment when the thyroid gland is still present
- But it remains valid in the presence of positive serum TgAb
- Recommendation 31 reviews the role of
FNA-Tg washout in lymph nodes in the postoperative setting
- Particularly in lymph nodes in the central compartment when the thyroid gland is still present
- Data are limited to support a definitive FNA-Tg threshold for diagnosis of a metastatic lymph node
- A systematic review and meta-analysis showed that FNA cytology with FNA-Tg washout has a negative predictive value (NPV) of 99.4% and accuracy of 86.8% in the evaluation of pathological-appearing lymph nodes:
- If the FNA-Tg level is 1.0 ng/mL or lower, then the NPV approximates 100%
- However, non-metastatic lymph nodes can have concentrations as high as 32 ng/mL
- Accuracy, specificity, positive predictive value (PPV), and NPV are significantly higher if the FNA-Tg threshold is 28.5 ng/mL
- Another systematic review analyzed 22 studies with 2,670 suspicious lymph nodes during thyroid nodule workup or PTC follow-up:
- Found that the highest sensitivity was observed with a FNA-Tg cut-off of 1 ng/mL and the highest specificity was observed with a cutoff of 40 ng/mL:
- In this study, other factors that influenced the accuracy of FNA-Tg included TSH suppression, presence of serum Tg, and methodologic differences in Tg measurement
- Found that the highest sensitivity was observed with a FNA-Tg cut-off of 1 ng/mL and the highest specificity was observed with a cutoff of 40 ng/mL:
- Another study found the presence of serum TgAb interferes with circulating serum Tg
measurement:- But does not appear to interfere with FNA-Tg measurements
- Further studies are needed to determine an optimal FNA-Tg threshold to diagnose metastatic lymph nodes
- Tg washout is a helpful adjunct to FNA:
- Is achieved by ultrasound-guided FNA aspiration for cytology and / or measurement of Tg in the needle washout (FNA-Tg):
- In addition to assessing for pathological lymph nodes:
- Ultrasound evaluation of the thyroid gland to gauge gross extrathyroidal extension is important for surgical planning:
- As this typically demonstrates indication for RAI and therefore total thyroidectomy
- Ultrasound evaluation of the thyroid gland to gauge gross extrathyroidal extension is important for surgical planning:
- If there is evidence of more advanced locoregional disease:
- Additional imaging with computed tomography (CT) may be useful
- While ultrasound is more specific for nodal disease:
- CT is more sensitive:
- The combination of both may increase diagnostic accuracy
- In view of the higher cost of CT compared with ultrasound, the associated radiation exposure, and potent risks of intravenous contrast administration in specific populations:
- It is important to determine the imaging needs on an individual patient basis
- Accurate staging is important for determining the prognosis and tailoring treatment for patients with DTC:
- However, unlike many tumor types, the presence of metastatic disease does not obviate the need for thyroidectomy:
- Because distant metastatic disease may respond to RAI therapy, removal
of the thyroid as well as the primary tumor and accessible loco-regional disease is an important component of initial treatment for most patients with distant metastatic disease
- Because distant metastatic disease may respond to RAI therapy, removal
- However, unlike many tumor types, the presence of metastatic disease does not obviate the need for thyroidectomy:
- CT is more sensitive:
Rodrigo Arrangoiz MS, MD, FACS, FSSO 