Workup of Lymph Node Found in Neck Ultrasound
The appropriate workup for a lymph node found on neck ultrasound should include ultrasound-guided fine-needle aspiration cytology (FNAC) as the initial diagnostic procedure, followed by additional imaging and possibly core biopsy depending on the FNAC results and clinical suspicion.
Initial Assessment of Neck Lymph Node
Ultrasound Characteristics to Evaluate
When a lymph node is identified on neck ultrasound, further characterization should include:
- Size measurements in three dimensions
- Echogenicity (hypoechoic nodes are more suspicious)
- Presence of microcalcifications (suspicious feature)
- Border characteristics (irregular borders suggest malignancy)
- Shape (round shape or "taller than wide" is suspicious)
- Absence of fatty hilum (suspicious feature)
- Vascular pattern on Doppler (peripheral vascularity is suspicious)
- Presence of cystic changes or necrosis
- Location within neck compartments (levels I-VI)
Risk Stratification Based on Ultrasound Features
The more suspicious features present, the higher the risk of malignancy 1. Suspicious features include:
- Hypoechogenicity
- Microcalcifications
- Irregular borders
- Round shape
- Absence of fatty hilum
- Peripheral vascularity
- Cystic changes
Diagnostic Procedures
Fine-Needle Aspiration Cytology (FNAC)
- FNAC should be the first-line diagnostic procedure for a suspicious lymph node 1
- Ultrasound-guided FNAC significantly improves diagnostic accuracy compared to palpation-guided techniques 2
- FNAC has been shown to detect malignancy in 13 out of 86 patients with normal palpation findings 2
Management of FNAC Results:
Adequate and diagnostic sample:
- If malignant: Proceed with appropriate staging and treatment
- If benign: Clinical follow-up with repeat ultrasound
Inadequate or indeterminate sample:
- Repeat FNAC with ultrasound guidance
- Consider on-site cytopathology evaluation to improve adequacy rates 1
Suspicion of lymphoma:
Core Needle Biopsy
- Consider after inadequate or indeterminate FNAC
- First-line approach when lymphoma is strongly suspected (92% sensitivity vs 74% for FNAC) 1
- Ultrasound-guided core biopsy has high adequacy rate (95%) and accuracy (94-96%) with low complication rate (1%) 1
Open Biopsy
- Reserved for cases where FNAC and core biopsy are non-diagnostic
- Should not be the first diagnostic approach in most cases
Additional Imaging Considerations
If malignancy is confirmed or strongly suspected, additional imaging may be necessary:
- CT or MRI with contrast: For comprehensive evaluation of the neck and potential primary tumor site 1
- PET/CT: Particularly valuable for suspected lymphoma or when searching for an unknown primary tumor 1
Special Considerations
Thyroid-Related Lymph Nodes
- If the lymph node is in the central neck compartment (level VI), consider thyroid evaluation
- Measure TSH and consider thyroid ultrasound 4
Suspected Squamous Cell Carcinoma
- Evaluate the upper aerodigestive tract for potential primary tumor
- Consider panendoscopy if no primary is identified on imaging 1
Suspected Lymphoma
- Core biopsy is preferred over FNAC for initial diagnosis 1, 3
- Flow cytometry may be helpful for diagnosis
Follow-up
- For benign-appearing lymph nodes with benign cytology: Follow-up ultrasound in 3-6 months
- For suspicious lymph nodes with benign cytology: Consider repeat FNAC or core biopsy
- For malignant lymph nodes: Appropriate oncologic management based on diagnosis
Common Pitfalls to Avoid
- Assuming a lymph node is benign based on size alone - small nodes can harbor micrometastases 2
- Relying solely on ultrasound features without cytologic confirmation 5
- Accepting a single negative FNAC in the presence of highly suspicious features 1
- Confusing anatomical structures (e.g., compressed veins) with lymph nodes 5
- Failing to evaluate the entire neck for additional abnormal lymph nodes 1
By following this systematic approach, clinicians can effectively evaluate lymph nodes found on neck ultrasound and determine the appropriate diagnostic and management strategy.