Evaluation and Management of Palpable Thyroid Nodules
All palpable thyroid nodules should be evaluated with thyroid function tests (TSH) first, followed by ultrasound, with fine-needle aspiration biopsy (FNAB) recommended for nodules ≥1 cm or smaller nodules with suspicious features. 1, 2
Initial Evaluation Algorithm
Step 1: Laboratory Assessment
- Begin with thyroid function tests, particularly TSH, as the first laboratory test for any patient with a thyroid nodule 1, 2
- TSH results will guide subsequent management approach 2, 3
Step 2: Management Based on TSH Results
If TSH is Low (Subnormal)
- Perform ultrasound to evaluate thyroid morphology 2, 3
- Follow with radionuclide thyroid uptake scan to determine if the nodule is hyperfunctioning 3
- Hyperfunctioning ("hot") nodules rarely require biopsy as they have very low malignancy risk 1, 3
If TSH is Normal or Elevated
- Proceed directly to ultrasound evaluation 1, 2
- Ultrasound will characterize the nodule for risk of malignancy 1, 3
Step 3: Ultrasound Evaluation
- Ultrasound provides high-resolution imaging to confirm the nodule is within the thyroid and characterize malignancy risk 1
- Suspicious ultrasound features include: 1
- Hypoechogenicity
- Microcalcifications
- Absence of peripheral halo
- Irregular borders
- Solid composition
- Intranodular blood flow
- Taller-than-wide shape
Step 4: Fine-Needle Aspiration Biopsy (FNAB)
- FNAB should be performed for: 1
- Any thyroid nodule >1 cm
- Nodules <1 cm with suspicious clinical features (history of radiation exposure, family history of thyroid cancer, suspicious palpation, cervical lymphadenopathy) or suspicious ultrasound features
- Ultrasound guidance improves accuracy of FNAB 4
Special Considerations
Multiple Nodules
- When multiple nodules are present, prioritize the largest nodule and those with suspicious ultrasound features for FNAB 4
- The American College of Surgeons recommends evaluation of thyroid nodules larger than 2 cm, even without suspicious features, due to increased malignancy risk 4
Indeterminate Cytology Results
- If FNAB results are indeterminate (follicular neoplasia), consider surgery when TSH is normal and the nodule appears "cold" on thyroid scan 1
- Molecular testing may help differentiate benign from malignant nodules in indeterminate cases 1
Small Nodules (<1 cm)
- Nodules ≤5 mm should generally be monitored rather than biopsied 5
- Nodules between 5-10 mm should only be biopsied when suspicious ultrasound signs are present 5
Common Pitfalls to Avoid
- Proceeding directly to radionuclide scan without first checking TSH levels 3
- Using radionuclide scanning to determine malignancy in euthyroid patients (low positive predictive value) 1
- Performing FNAB without ultrasound guidance (increases risk of insufficient specimens) 6
- Over-treatment of benign thyroid nodules with unnecessary surgery 7
- Relying solely on nodule size without considering other risk factors for malignancy 8
Follow-up Recommendations
- For benign nodules (Bethesda category II), the risk of malignancy is very low (1-3%) 4
- Most thyroid nodules do not require treatment, and levothyroxine suppressive therapy is not recommended 5
- Surgery remains the treatment of choice for malignant or suspicious nodules 5, 9
- Percutaneous ethanol injection should be considered for relapsing benign cystic lesions 5