A 44-year-old woman presents with a lump in the neck noticed six weeks ago. She is clinically euthyroid, with no compressive symptoms, no family history of thyroid disease and no history of neck irradiation. Examination shows a 2.5 cm firm nodule in the right thyroid lobe moving with swallowing, with no palpable lymphadenopathy. Thyroid function tests are normal. Ultrasound characterises the nodule as U3 (indeterminate) with no suspicious cervical nodes. What is the most appropriate next step?
- AReassure and discharge, as most thyroid nodules are benign
- BRadioisotope thyroid scan to characterise the nodule
- CDiagnostic right hemithyroidectomy without prior cytology
- DUltrasound-guided fine needle aspiration cytology of the nodule
- EContrast-enhanced CT of the neck and thorax
Show answer and explanation
Correct answer: D
Assessment of a thyroid nodule follows a defined pathway: clinical evaluation, thyroid function tests, and ultrasound grading (U1 to U5 in UK practice). A euthyroid patient with a U3 (indeterminate) nodule requires ultrasound-guided fine needle aspiration cytology, reported on the Thy1 to Thy5 scale, which then directs management — from routine follow-up for benign Thy2 findings to diagnostic or therapeutic surgery for Thy3 to Thy5. Ultrasound guidance improves adequacy rates substantially over palpation-guided sampling, and cytology, not imaging, is what stratifies malignant risk in an indeterminate nodule.
Why the others are wrong: A — although most nodules are benign, a U3 nodule carries a meaningful malignancy risk and cannot be dismissed without cytology. B — isotope scanning is reserved for the thyrotoxic patient with a nodule, to identify a hot (autonomously functioning, almost never malignant) nodule that does not need FNA; in a euthyroid patient it adds nothing. C — surgery without cytology subjects many patients with benign disease to an operation with recurrent laryngeal nerve and parathyroid risk; surgery follows cytological stratification. E — CT assesses retrosternal extension and compressive disease; it does not characterise malignant risk, and iodinated contrast complicates any subsequent radioiodine therapy.
Key point: A euthyroid patient with an ultrasound-indeterminate (U3) thyroid nodule needs ultrasound-guided FNA cytology — the Thy grade, not imaging alone, determines whether surgery is required; isotope scanning is reserved for the toxic patient.
Guidelines: British Thyroid Association guidelines 2014: ultrasound grading (U1-U5) with ultrasound-guided FNA cytology (Thy classification) is the standard first investigation of a thyroid nodule; NICE thyroid disease guidance (NG145).