What is the next step in evaluating a palpable thyroid mass with a movable lump?

Management of a Palpable Thyroid Mass

For a palpable thyroid mass with a movable lump, the next step should be thyroid function tests (TSH, Free T3, Free T4) followed by a thyroid ultrasound. 1, 2

Initial Evaluation Algorithm

1. Thyroid Function Tests

   • Measure TSH, Free T3, and Free T4 to assess thyroid function 2
   • If TSH is subnormal (suppressed), perform a thyroid scan with 99Tc to evaluate for hot nodules 1, 3
   • If TSH is normal or elevated, proceed with ultrasound evaluation

2. Thyroid Ultrasound

   • Ultrasound is the preferred first-line imaging modality for all palpable thyroid nodules 1, 2
   • Provides high-resolution imaging to confirm the palpable abnormality is within the thyroid
   • Characterizes the nodule for malignancy risk based on specific sonographic features

3. Risk Stratification Using TI-RADS

   • Evaluate ultrasound features that suggest increased malignancy risk 2:
     • Solid composition
     • Hypoechogenicity
     • Irregular/blurred margins
     • Microcalcifications
     • Absence of peripheral halo
     • Taller-than-wide shape

4. Fine Needle Aspiration (FNA)

   • Perform FNA for nodules based on size and TI-RADS category 2:
     • Nodules ≥1 cm with suspicious features
     • Any size nodule with highly suspicious features in high-risk patients
     • Nodules causing compressive symptoms

Ultrasound Features and Malignancy Risk

Ultrasound features strongly associated with malignancy include 1, 4:

• Microcalcifications (OR: 159)
• Blurred/ill-defined margins (OR: 37)
• Solid composition (OR: 9.9)
• Hypoechogenicity (OR: 2.2)

Most malignant nodules have more than two suspicious ultrasound features 5.

Important Considerations

• Ultrasound-guided FNA has higher sensitivity, specificity, and accuracy than palpation-guided techniques 5
• Calcitonin measurement should be considered as part of the diagnostic evaluation to detect medullary thyroid cancer, as it has higher sensitivity than FNA 1, 2
• CT or MRI is generally not needed for initial evaluation unless there is suspicion of substernal extension or invasive cancer 1
• Radionuclide scanning is not helpful in determining malignancy in euthyroid patients 1

Common Pitfalls to Avoid

1. Skipping thyroid function tests: Always check thyroid function before proceeding with imaging, as this affects the diagnostic pathway 1, 2

2. Overreliance on a single ultrasound feature: No single ultrasound feature can definitively diagnose malignancy; multiple features should be considered together 4

3. Unnecessary biopsy of all nodules: Not all nodules require FNA; follow evidence-based criteria based on size and ultrasound characteristics 2

4. Overlooking clinical risk factors: Consider patient age (young age is a risk factor), history of radiation exposure, and family history of thyroid cancer when assessing nodules 2

5. Neglecting to assess for compressive symptoms: Evaluate for dyspnea, dysphagia, or dysphonia, which may indicate the need for surgical intervention regardless of malignancy risk 1, 6

By following this systematic approach, you can efficiently evaluate a palpable thyroid mass and determine the appropriate next steps for management.