What is the next step in managing a patient with a multinodular thyroid gland and bilateral solid nodules, including one with worrisome appearance and a calcified focus?

Management of Multinodular Thyroid Gland with Worrisome Nodules

Immediate Next Steps

Fine-needle aspiration biopsy (FNAB) should be performed on the worrisome nodule in the left lobe (0.88 x 0.53 cm with internal vascularity) and the calcified focus (0.62 x 0.54 cm) as the highest priority. 1

The ultrasound findings reveal several concerning features that warrant immediate investigation:

• Multinodular appearance with heterogeneous texture
• Overall increased vascularity
• A left lobe nodule with internal vascularity (0.88 x 0.53 cm)
• A calcified focus in the left lobe (0.62 x 0.54 cm)

Diagnostic Approach

1. Thyroid Function Tests:

   • Measure TSH, free T4, and free T3 to assess thyroid function status
   • If TSH is subnormal, consider radioisotope scanning before biopsy 1

2. Serum Calcitonin Measurement:

   • Essential to rule out medullary thyroid cancer
   • Has higher sensitivity than FNAC for detecting medullary thyroid cancer 1

3. Ultrasound-Guided FNAB:

   • Target the nodule with internal vascularity (0.88 x 0.53 cm)
   • Target the calcified focus (0.62 x 0.54 cm)
   • Calcifications within thyroid nodules significantly increase malignancy risk (59.2% of nodules with calcifications were found to be malignant in one study) 2

4. Consider Additional Imaging:

   • If there is concern for substernal extension, CT or MRI may be needed 1
   • Avoid iodinated contrast if radioactive iodine therapy might be needed later 3

Rationale for FNAB

FNAB is indicated based on several high-risk features:

• The presence of internal vascularity in the left lobe nodule
• The calcified focus in the left lobe (calcification is associated with higher risk of malignancy)
• Heterogeneous texture with multinodular appearance

While the nodules are smaller than 1 cm (typically the size threshold for biopsy), the presence of suspicious sonographic features warrants FNAB regardless of size 1.

Management Algorithm Based on FNAB Results

If FNAB Shows Malignancy:

1. Surgical Management:

   • Total thyroidectomy is recommended for:
     • Bilateral nodularity
     • Presence of aggressive variants
     • Nodules with concerning features 3
   • Consider central neck dissection (level VI) if lymph nodes are positive 3

2. Post-Surgical Evaluation:

   • Consider radioiodine ablation based on risk stratification
   • TSH suppression with levothyroxine 3

If FNAB Shows Indeterminate Results:

1. Consider molecular testing to further stratify risk
2. Surgical consultation for possible diagnostic lobectomy
3. Close follow-up with repeat ultrasound in 3-6 months

If FNAB Shows Benign Results:

1. Regular ultrasound monitoring:
   • Initial follow-up at 6-12 months
   • Then annually if stable 1
2. Repeat FNAB if significant growth occurs or new suspicious features develop

Important Considerations

• The presence of calcification significantly increases malignancy risk, with studies showing up to 75.7% risk of malignancy in solitary nodules with calcification 2
• Internal vascularity is another concerning feature that increases suspicion for malignancy
• Even with benign FNAB results, close follow-up is essential as false negatives can occur, particularly with calcified nodules 2
• Avoid relying solely on reassuring FNAB results when clinical and sonographic findings are worrisome 1

Pitfalls to Avoid

• Dismissing calcifications as incidental findings (they significantly increase malignancy risk)
• Neglecting to measure calcitonin (could miss medullary thyroid cancer)
• Failing to have cytology reviewed by a pathologist with expertise in thyroid disorders
• Delaying surgical consultation when there are multiple concerning features

The presence of both a nodule with internal vascularity and a calcified focus in the left lobe represents a significant risk for malignancy that requires prompt evaluation with FNAB, regardless of the small size of these nodules.