What is the next step in managing a patient with multiple solid hypoechogenic thyroid nodules, including a 1.1 x 1.0 x 0.6 cm nodule in the right lobe and a 0.7 x 0.5 x 0.5 cm nodule in the left lobe, with no suspicious features, normal thyroid size, and symmetrical lobes?

Management of Multiple Solid Hypoechoic Thyroid Nodules

Perform ultrasound-guided fine-needle aspiration (FNA) biopsy of the largest nodule (1.1 cm right lobe nodule), as solid hypoechoic nodules ≥1 cm require cytological evaluation regardless of the absence of other suspicious features. 1

Rationale for FNA in This Case

Your patient has multiple solid hypoechoic nodules, with the largest measuring 1.1 cm. While the nodules lack highly suspicious features (no microcalcifications, irregular margins, or abnormal vascularity), the combination of solid composition and hypoechoic appearance warrants tissue diagnosis. 1

• Solid composition carries higher malignancy risk compared to cystic nodules, and hypoechogenicity is a well-established suspicious sonographic feature. 1
• Guidelines recommend FNA for any nodule >1 cm with suspicious ultrasonographic features such as hypoechogenicity, even when other high-risk features are absent. 1
• The 1.1 cm nodule meets the size threshold where FNA is indicated based on current evidence. 1, 2

Why the Absence of Other Suspicious Features Doesn't Change Management

The smooth borders, absence of microcalcifications, and lack of abnormal vascularity are reassuring but do not eliminate the need for FNA in a 1.1 cm solid hypoechoic nodule. 1

• Solid hypoechoic nodules ≥1 cm require FNA even without additional suspicious features, as malignancy cannot be reliably excluded by ultrasound alone. 1, 3
• The heterogeneous thyroid echotexture suggests possible underlying thyroiditis, but this does not preclude malignancy in discrete nodules. 1
• False-negative rates increase when FNA is deferred based solely on the absence of microcalcifications or irregular margins. 1

Procedural Approach

Target the largest nodule (1.1 cm right lobe) for initial FNA under ultrasound guidance. 1

• Ultrasound guidance ensures accurate sampling and is superior to palpation-guided biopsy. 1
• Obtain 2-4 aspirations from different areas of the nodule to maximize diagnostic yield. 4
• Request cytopathology reporting using the Bethesda Classification System (categories I-VI). 1, 5

Management Based on FNA Results

If Bethesda II (Benign)

• Initiate surveillance with repeat ultrasound at 12-24 months to monitor for interval growth or development of suspicious features. 1, 6
• The malignancy risk with benign cytology is only 1-3%, making surveillance appropriate. 1
• Consider FNA of the smaller nodules only if they demonstrate growth ≥3 mm or develop new suspicious features during follow-up. 6

If Bethesda III (AUS/FLUS) or IV (Follicular Neoplasm)

• Consider molecular testing (BRAF, RAS, RET/PTC, PAX8/PPARγ) to refine malignancy risk and guide surgical decision-making. 1, 7
• Repeat FNA or core needle biopsy may be indicated if initial sample is inadequate. 1

If Bethesda V (Suspicious) or VI (Malignant)

• Refer immediately to an endocrine surgeon for total or near-total thyroidectomy. 1
• Perform pre-operative neck ultrasound to assess cervical lymph node status. 1

If Bethesda I (Nondiagnostic/Inadequate)

• Repeat FNA under ultrasound guidance is mandatory, as inadequate samples occur in 5-20% of cases. 1, 4

Additional Diagnostic Considerations

• Measure serum TSH before FNA to determine if the nodules are autonomously functioning. 1, 7, 5
• If TSH is suppressed, obtain a radionuclide thyroid scan to identify hyperfunctioning nodules, which are rarely malignant and do not require FNA. 1, 7
• Measure serum calcitonin as part of the diagnostic workup to screen for medullary thyroid cancer, which has higher sensitivity than FNA alone. 1

Management of the Smaller Nodules

The 0.7 cm nodules in both lobes do not require immediate FNA unless high-risk clinical factors are present. 1

• High-risk factors that would lower the FNA threshold include: history of head/neck irradiation, family history of thyroid cancer, suspicious cervical lymphadenopathy, or age <15 years. 1
• Monitor these smaller nodules with surveillance ultrasound at the same intervals as the biopsied nodule. 6
• Perform FNA of smaller nodules if they grow ≥3 mm, reach 1 cm, or develop suspicious features (microcalcifications, irregular borders, marked hypoechogenicity). 1, 6

Surveillance Schedule for All Nodules

Following initial FNA, establish a structured surveillance protocol: 6

• First follow-up ultrasound at 12 months to establish nodule stability and detect early changes. 6
• Subsequent ultrasounds at 24 and 60 months after initial evaluation. 6
• At each visit, measure nodule dimensions in three planes, assess for new suspicious features, and screen for new nodules. 6

Critical Pitfalls to Avoid

• Do not defer FNA based solely on smooth borders and absence of microcalcifications in a 1.1 cm solid hypoechoic nodule—these features do not reliably exclude malignancy. 1, 3
• Do not assume heterogeneous thyroid echotexture indicates only benign thyroiditis—discrete nodules within thyroiditis still require evaluation. 1
• Do not perform FNA on all nodules simultaneously—prioritize the largest nodule first, as this is the standard approach when multiple nodules are present. 1
• Do not rely on thyroid function tests (TSH, T3, T4) for malignancy assessment, as most thyroid cancers present with normal thyroid function. 1