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Difficulty: MediumBreast and Endocrine Surgery

A 35-year-old woman presents to the clinic after noticing a lump in her neck while applying lotion. She denies weight changes, palpitations, heat or cold intolerance, or changes in bowel habits. She has no family history of thyroid disease or head and neck irradiation. Vital signs are within normal limits. Physical examination reveals a 1.5-cm, firm, mobile nodule in the left lobe of the thyroid gland. There is no cervical lymphadenopathy. Laboratory studies show a thyroid-stimulating hormone (TSH) level of 2.8 µU/mL (normal: 0.4–4.0 µU/mL) and a free T4 of 1.2 ng/dL (normal: 0.9–2.4 ng/dL). An ultrasound of the neck demonstrates a 1.6-cm solid, hypoechoic nodule with irregular margins and microcalcifications in the left thyroid lobe. Which of the following is the most appropriate next step in management?

  1. Fine-needle aspiration biopsyAnswer
  2. B
    Radionuclide thyroid scan
  3. C
    Reassurance and repeat ultrasound in 12 months
  4. D
    Measurement of serum thyroglobulin level
  5. E
    Left thyroid lobectomy

Answer

The most appropriate next step is a fine-needle aspiration biopsy of the thyroid nodule.
The correct approach for evaluating a palpable thyroid nodule involves initially checking a serum TSH and performing a neck ultrasound. If the TSH is normal or elevated, the nodule is nonfunctioning, and the risk of malignancy must be assessed via ultrasound. This patient has a 1.6-cm nodule with highly suspicious features (solid, hypoechoic, irregular margins, and microcalcifications). Guidelines recommend fine-needle aspiration (FNA) biopsy for highly suspicious nodules that are >1 cm in diameter to obtain a cytological diagnosis and rule out thyroid cancer.

Step-by-Step Solution

1
Evaluate the initial laboratory findings for the palpable thyroid nodule.
The patient's TSH level is within normal limits (2.8 µU/mL).
The TSH level determines the functional status of the nodule and dictates whether a functional (radionuclide) scan is required.
2
Assess the ultrasound findings in the context of a normal TSH level.
Ultrasound reveals a 1.6-cm solid, hypoechoic nodule with microcalcifications and irregular margins.
These specific sonographic features are highly suspicious for a thyroid malignancy, such as papillary thyroid carcinoma.
3
Determine the indications for a diagnostic biopsy.
A fine-needle aspiration (FNA) biopsy is indicated.
FNA is required for any solid thyroid nodule >1 cm that exhibits high-risk sonographic features to obtain a definitive cytological diagnosis prior to planning potential surgery.

Key Concept

Diagnostic algorithm and indications for fine-needle aspiration of a thyroid nodule.
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Topics

Breast and Endocrine Surgery

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