Thyroid Nodules

When to Investigate:

• Any palpable thyroid nodule warrants an ultrasound (US) evaluation.

• In cases with high cancer risk (i.e., hoarseness, lymphadenopathy, rapid growth, or history of radiation exposure), a fine-needle aspiration (FNA) biopsy may be performed directly without a preliminary radioisotope scan.

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History: 

Key symptoms and clinical history include:

• Symptoms of hypo- or hyperthyroidism.

• Respiratory symptoms, i.e., cough and dyspnoea.

• Voice changes, i.e., hoarseness.

• Swallowing difficulties, i.e., dysphagia.

Initial Evaluation and Workup:

• TSH Measurement: Initial thyroid function assessment.

  • If TSH is normal or elevated, proceed with ultrasound to evaluate FNA need.

  • If TSH is subnormal, conduct a radionuclide scan to assess functionality.

If Hyperthyroid:

• Radionuclide scan to assess whether the nodule is hyperfunctioning (hot) or hypofunctioning (cold).

  • Hyperfunctioning (Hot): Rarely malignant; FNA usually not necessary.

  • Hypofunctioning (Cold): Consider FNA if US criteria for malignancy are met.

If Hypothyroid:

• Proceed to FNA if US findings meet criteria for malignancy.

• FNA is not indicated if no palpable lump is present in a hypothyroid patient.

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Follow-Up and Surveillance:

Based on sonographic and FNA findings:

• Very Low-Risk Nodules: No surveillance required for >24 months.

• Low/Intermediate Risk: Surveillance every 1–2 years.

• High Risk: Follow-up within 6–12 months.

• Non-Benign or Indeterminate Results: Refer to a specialist for further management.

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Risk Stratification and Bethesda System:

• FNA results categorized using the Bethesda System, which guides management based on malignancy risk:

  • Non-diagnostic/Unsatisfactory (5–10%): Repeat FNA or refer to an endocrinologist.

  • Benign (0–3%): Follow-up based on sonographic risk.

  • Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance (AUS/FLUS, 10–30%): Endocrinology referral.

  • Follicular Neoplasm/Suspicious for Follicular Neoplasm (FN/SFN, 25–40%): Specialist referral.

  • Suspicious for Malignancy (50–75%): High likelihood; refer to a thyroid surgeon.

  • Malignant (97–99%): High likelihood of malignancy; surgical intervention recommended.

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Notes:

• Surveillance intervals may be adjusted depending on the Bethesda category and sonographic features.

• The Bethesda System aids in standardized reporting and management decisions based on FNA cytology.