For a patient with a 2 cm firm, non‑tender, mobile thyroid nodule on ultrasound and otherwise normal exam, should we observe for 4–6 weeks or perform fine‑needle aspiration (FNA)?

Management of a 2 cm Firm, Non-Tender, Mobile Thyroid Nodule

Fine-needle aspiration (FNA) is the most appropriate next step for this patient, not observation. 1

Rationale for Immediate FNA

The presence of a 2 cm thyroid nodule mandates tissue diagnosis regardless of other features. Current guidelines universally recommend FNA for any thyroid nodule ≥1 cm, and this patient's nodule is twice that threshold. 2, 1, 3

Key Supporting Evidence:

• Size alone is a critical determinant: The American Thyroid Association and National Comprehensive Cancer Network recommend FNA for nodules >1 cm, even without suspicious ultrasound features. 1

• Malignancy risk considerations: While thyroid nodules are common (50% prevalence on ultrasound), approximately 5-15% harbor malignancy. 2, 3 A 2 cm nodule carries sufficient risk to warrant cytological evaluation rather than observation.

• Diagnostic accuracy: FNA achieves approximately 95% diagnostic accuracy when properly performed, making it the gold standard for preoperative thyroid nodule evaluation. 1, 3

Why Observation (4-6 Weeks) is Inappropriate

Waiting 4-6 weeks serves no diagnostic purpose for a solid thyroid nodule. 1

• Short-term observation is reserved for specific scenarios such as suspected infectious/inflammatory processes or post-procedural changes—none of which apply to this presentation. 2

• The nodule characteristics described (firm, mobile, non-tender) suggest a chronic process requiring tissue diagnosis, not a transient condition that would resolve with observation. 2

• Delaying diagnosis by 4-6 weeks provides no additional clinical information and only postpones necessary evaluation. 1

Procedural Approach

Ultrasound-guided FNA should be performed rather than palpation-guided biopsy, even though the nodule is palpable. 1, 4

Technical specifications:

• Ultrasound guidance allows real-time needle visualization, confirms accurate sampling, and is superior to palpation-guided biopsy in accuracy and diagnostic yield. 1

• The procedure should document nodule characteristics including echogenicity, margins, calcifications, and vascularity to complete risk stratification. 1

• If the nodule appears heterogeneous on ultrasound, targeted sampling of suspicious areas is essential. 4

Management Based on FNA Results

Bethesda II (Benign):

• Surveillance with repeat ultrasound at 12-24 months. 1
• Malignancy risk only 1-3%. 1

Bethesda III/IV (Indeterminate):

• Consider molecular testing (BRAF, RAS, RET/PTC, PAX8/PPARγ) to refine malignancy risk. 1
• Surgical consultation if high-risk features present. 1

Bethesda V/VI (Suspicious/Malignant):

• Immediate referral to endocrine surgeon for total or near-total thyroidectomy. 1
• Pre-operative neck ultrasound to assess lymph node status. 1

Common Pitfalls to Avoid

• Do not delay FNA based on nodule mobility or lack of tenderness—these features do not reliably exclude malignancy. 2

• Do not order thyroid function tests (TSH) as a substitute for FNA—most thyroid cancers occur in euthyroid patients. 1

• Do not rely on clinical examination alone—palpation cannot distinguish benign from malignant nodules with sufficient accuracy. 2, 3

• Do not perform radionuclide scanning in euthyroid patients—it does not help determine malignancy risk and delays appropriate evaluation. 1