How to manage a thyroid nodule?

Management of Thyroid Nodules

The management of thyroid nodules begins with measuring serum TSH to determine the diagnostic pathway, followed by ultrasound evaluation and ultrasound-guided fine-needle aspiration biopsy (FNAB) for risk stratification, with most benign nodules requiring only surveillance while malignant or suspicious nodules warrant surgical intervention. 1, 2

Initial Diagnostic Algorithm

Step 1: Measure Serum TSH

• TSH is the single best initial test and determines all subsequent management decisions 2
• If TSH is low or suppressed: proceed to radioiodine uptake scan to identify hyperfunctioning ("hot") nodules, which are rarely malignant and do not require FNA 2
• If TSH is normal or elevated: proceed directly to ultrasound evaluation without radionuclide scanning 2

Step 2: Thyroid Ultrasound Evaluation

• Perform ultrasound of the thyroid and central neck in all patients with palpable nodules 2
• High-risk ultrasound features requiring FNA include:
  • Microcalcifications 2
  • Central hypervascularity 2
  • Taller-than-wide shape 2
  • Solid composition with hypoechogenicity 3
  • Irregular margins 3

Step 3: Fine-Needle Aspiration Biopsy

• All patients with thyroid nodules require ultrasound-guided FNAB to confirm pathological diagnosis before determining management, as this is the most accurate and cost-effective method 1
• FNA is indicated for nodules >1 cm with suspicious features 4
• For nodules <10 mm, FNA is recommended only if clinical or ultrasound features are suspicious 5

Clinical Risk Stratification

High-risk clinical features for thyroid cancer include: 2

• Age <15 years or male gender
• History of head and neck irradiation
• Family history of thyroid cancer or associated syndromes (MEN 2A/2B, familial adenomatous polyposis, Carney complex, Cowden's syndrome)
• Firm, fixed, rapidly growing nodule
• Associated cervical lymphadenopathy
• Vocal cord paralysis or symptoms of invasion

Management Based on Cytology Results

Benign Nodules

• Most benign thyroid nodules require no treatment and should undergo surveillance 1
• Treatment indications for benign nodules include: 1
  • Nodules causing compression symptoms
  • Nodules ≥2 cm with gradual enlargement
  • Cosmetic concerns
  • Autonomously functioning nodules causing hyperthyroidism

Malignant or Suspicious Nodules

• Surgery remains the treatment of choice for nodules with malignant or suspicious cytology 1
• The extent of surgery depends on postoperative risk stratification using the American Thyroid Association's low-, intermediate-, and high-risk classification system 1

Thermal Ablation as Alternative for Select Cases

• Thermal ablation may be considered for very specific papillary thyroid cancers meeting strict criteria: 1
  • Single nodule with maximal diameter ≤1 cm
  • Classical variant papillary thyroid carcinoma confirmed by biopsy
  • No invasion of trachea, large blood vessels, or perithyroid structures
• Following thermal ablation of malignant nodules, TSH suppression therapy is mandatory with target TSH 0.5-2.0 mU/L for absolute indications and <0.5 mU/L for relative indications 1

Follow-Up Protocol

For Untreated Benign Nodules

• Initial ultrasound surveillance at 12-month intervals 1, 2
• Repeat FNA if nodule increases by ≥3 mm in any dimension or develops new suspicious features 2
• Low-risk patients with nodules <6 mm without suspicious features may not require routine follow-up 2

For Post-Ablation Nodules

• First follow-up at 1 month, then at 3,6, and 12 months during the first year 6, 1
• After 12 months, re-evaluate malignant nodules every 6 months and benign nodules annually 6
• Follow-up should include volume reduction rate (VRR), improvements in compression symptoms and cosmetic concerns, presence of residual nodules, recurrence, metastasis, recovery from complications, and thyroid function 6

Important Caveats

• Do not routinely measure serum calcitonin in all patients with thyroid nodules, as cost-effectiveness is not established in the United States 2
• Cystic or spongiform appearance on ultrasound suggests a benign process that does not require additional testing 3
• Molecular testing is indicated only in selected cases, such as indeterminate cytology (20-30% of all biopsies) 3