What is the most appropriate management for a patient with toxic multinodular goiter (TMNG) and a 2 cm solid nodule on ultrasound (US)?

Management of Toxic Multinodular Goiter with a 2 cm Solid Nodule

The most appropriate management for a patient with toxic multinodular goiter (TMNG) and a 2 cm solid nodule on ultrasound is radioiodine (RAI) ablation.

Diagnostic Considerations

When evaluating a patient with TMNG and a 2 cm solid nodule, several factors must be considered:

• The presence of hyperthyroidism (toxic state)
• The multinodular nature of the goiter
• The size of the dominant nodule (2 cm)
• The solid appearance on ultrasound
• The thyroid scan showing toxic multinodular goiter pattern

Treatment Algorithm

Step 1: Risk Assessment

• Evaluate the 2 cm solid nodule for malignancy risk
  • If fine needle aspiration (FNA) shows benign cytology, proceed with treatment for TMNG
  • If FNA shows suspicious or malignant cytology, surgical management would be preferred

Step 2: Treatment Selection for TMNG with Benign Nodule

• Radioiodine (RAI) ablation is the first-line therapy for most patients with TMNG, particularly when:
  • The patient has no compressive symptoms
  • The goiter is not extremely large
  • There is no evidence of malignancy

Step 3: Surgical Considerations

Surgery would be indicated in specific circumstances:

• Presence of compressive symptoms
• Very large goiter with substernal extension
• Suspicious or malignant cytology
• Patient preference or contraindication to RAI

Rationale for RAI Ablation

RAI ablation is preferred for TMNG because:

1. It effectively treats the hyperthyroidism by destroying the autonomously functioning thyroid tissue
2. It avoids the risks associated with surgery (recurrent laryngeal nerve injury, hypoparathyroidism)
3. It can be performed as an outpatient procedure
4. It provides definitive treatment for the toxic state

Surgical Options (When Indicated)

If surgery is required due to specific indications mentioned above:

• Near-total or total thyroidectomy would be preferred over subtotal thyroidectomy for TMNG
• This approach minimizes the risk of recurrence, which can be up to 50% with subtotal procedures 1
• Right thyroidectomy alone would be inadequate for multinodular disease affecting both lobes

Common Pitfalls to Avoid

1. Undertreating with subtotal thyroidectomy: This carries a high recurrence risk of up to 50% 1
2. Performing hemithyroidectomy for multinodular disease: This fails to address disease in the contralateral lobe
3. Delaying treatment of toxic state: Untreated hyperthyroidism carries cardiovascular risks
4. Failing to evaluate nodules for malignancy: Incidental thyroid cancers are detected in 3-16.6% of apparently benign goiters 1

Follow-up After Treatment

• Monitor thyroid function tests 2-3 months after treatment
• Initiate levothyroxine therapy as needed after RAI ablation
• Annual follow-up to assess for recurrence or development of hypothyroidism

In conclusion, while surgical options may be necessary in specific cases, RAI ablation represents the most appropriate first-line management for most patients with toxic multinodular goiter and a solid nodule without suspicious features or compressive symptoms.