A 55-year-old woman presents to the primary care clinic for her annual visit. She has no complaints and is asymptomatic. She has a history of hypertension, hyperlipidemia, and diabetes. Her medications are lisinopril, amlodipine, atorvastatin, and metformin. There is no family history of malignancy. She is a non-smoker and drinks 3-4 standard drinks per week. Her temperature is 98.2°F (36.8°C), blood pressure is 142/84 mmHg, pulse is 82/min, and respirations are 16/min. On physical exam, a solid, immobile neck mass is palpated inferior to the cricoid cartilage to the left of midline. An ultrasound is obtained and shows a 1.2 cm hypoechoic mass with microcalcifications. Serum thyroid-stimulating hormone (TSH) concentration is 7.2 µU/mL. Which of the following is the most appropriate next step in management?
Propylthiouracil
Fine needle aspiration
Radioiodine ablation
Surgical removal of the mass
Fine needle aspiration
This patient’s presentation with an asymptomatic thyroid nodule with suspicious ultrasound features (≥ 1 cm hypoechoic mass with microcalcifications) and elevated TSH is concerning for thyroid malignancy. The most appropriate next step in management is a fine needle aspiration (FNA).

The first step in the diagnostic work-up of a thyroid nodule, which can be found incidentally in asymptomatic individuals or in the presence of obstructive or vocal symptoms, includes an ultrasound and measurement of serum TSH levels. If TSH is normal or elevated, this suggests a hypofunctioning (“cold”) nodule, which increases the risk of cancer. These nodules should undergo FNA if suspicious sonographic findings are present. Suspicious sonographic findings include irregular margins, microcalcifications, taller-than-wide shape, and rim calcifications in nodules ≥ 1 cm in diameter. If TSH is low, then thyroid scintigraphy (radioiodine scan) should be performed to confirm whether the nodule is hyperfunctioning (“hot”). Hyperfunctioning nodules are rarely cancerous, so these patients can often avoid FNA. Hyperfunctioning nodules such as toxic adenomas which cause overt hyperthyroid symptoms may warrant further treatment with radioiodine, surgery, or anti-thyroid medications.

Durante et al. review the epidemiology and diagnostic approach to thyroid nodules. The authors find that nodules with suspicious sonographic patterns such as solid composition, hypoechogenicity, irregular margins, and microcalcifications should undergo cytological evaluation. The authors recommend molecular testing only in cases in which cytology is indeterminate.

Incorrect Answers:
Answer B: Propylthiouracil is a thionamide that inhibits thyroid peroxidase, thus preventing thyroid hormone synthesis. It can be used for the symptomatic control of hyperthyroidism in toxic adenomas prior to definitive surgical resection. It is not indicated for the treatment of a hypofunctioning nodule.

Answer C: Radioiodine ablation can be used in the treatment of a toxic adenoma, which would take up the radioactive iodine. It is not indicated for the treatment of a hypofunctioning nodule, which would not exhibit radioiodine uptake.

Answer D: Surgical removal of the mass is a treatment option for a malignant thyroid nodule. Although a hypofunctioning nodule is more likely to be malignant, an FNA should be performed first to confirm the diagnosis.

Answer E: Thyroid scintigraphy is used for thyroid nodules with low TSH, which increases the probability of a hyperfunctioning nodule. Confirmation of a hyperfunctioning nodule can help prevent further invasive diagnostic work-up because hyperfunctioning nodules are unlikely to be malignant. Thyroid scintigraphy would not be appropriate in this patient with an elevated TSH.

Bullet Summary:
The next step in management for a thyroid nodule with suspicious sonographic features and an elevated TSH is fine needle aspiration.