Thyroid nodules, goitre and thyroid cancer — formative SAQs

SAQ 1 (10)

A 14-year-old girl finds a painless lump in her right neck. Examination shows a 2 cm firm but mobile right-lobe thyroid nodule with no cervical lymphadenopathy and a normal voice. She is clinically euthyroid with no prior radiation and no family history of thyroid cancer. [1]

1. Outline the investigation sequence for this nodule. (3) [1]
2. State the role of ACR TI-RADS and Bethesda cytology. (3) [1] [2]
3. Give two red-flag features that would accelerate referral. (2) [1]
4. Why is the malignancy risk higher than in an adult? (2) [5]

Model answer

Investigation sequence. TSH with reflex free T4 to establish functional status (a suppressed TSH with a solitary nodule suggests a hyperfunctioning, almost always benign lesion); high-frequency thyroid ultrasound applying ACR TI-RADS to the nodule and mapping cervical nodes; ultrasound-guided FNA of any nodule meeting TI-RADS threshold, reported with Bethesda cytology; add molecular testing if the cytology is indeterminate. [1]

TI-RADS and Bethesda. TI-RADS scores composition, echogenicity, shape, margin and echogenic foci into a tier (TR1 benign to TR5 highly suspicious) with size-based FNA thresholds — here a 2 cm TR4 lesion meets the threshold. Bethesda cytology assigns one of six categories (I non-diagnostic through VI malignant) whose malignancy risk frames the next step; Bethesda V/VI prompts multidisciplinary surgical referral. [1] [2]

Red flags. Firm or fixed mass with new hoarseness (recurrent laryngeal nerve), and associated firm or matted cervical lymphadenopathy; others include rapid growth and compressive symptoms. [1]

Higher paediatric risk. Childhood nodules carry roughly 20–25% malignancy risk — about double the adult ~10–15% — reflecting a more aggressive biological substrate and the gene-fusion driver profile distinct from adult BRAF V600E point-mutation disease. [5]

SAQ 2 (10)

A 12-year-old boy undergoes ultrasound-guided FNA of a right-lobe nodule. Cytology returns Bethesda VI (malignant). Staging ultrasound shows an enlarged right central neck node. He is euthyroid. [1]

1. Who should operate, and what procedure is planned? (3) [1] [20]
2. Outline the role of radioiodine using the ATA paediatric risk framework. (3) [1]
3. How is long-term surveillance conducted? (2) [1]
4. How would the plan change if calcitonin were markedly elevated? (2) [13]

Model answer

Surgery. A high-volume thyroid surgeon within a paediatric multidisciplinary thyroid team performs total or near-total thyroidectomy with central (and lateral, if positive) neck dissection for the nodal disease. High-volume operating matters because recurrent laryngeal nerve injury and hypoparathyroidism are operator-dependent and carry lifelong consequences in a child. [1] [20]

Radioiodine. After surgery, ATA 2015 paediatric risk stratification assigns low, intermediate or high risk; radioiodine (I-131) is selective — reserved for intermediate- and high-risk differentiated disease — with TSH suppression during active disease and relaxation once in durable remission. [1]

Surveillance. Thyroglobulin (Tg) trend alongside neck ultrasound, with stimulated Tg and cross-sectional or functional imaging if recurrence is suspected; response is defined by structural and biochemical remission (undetectable Tg, negative imaging). [1]

Calcitonin elevation. A markedly raised calcitonin shifts the diagnosis toward medullary (C-cell) carcinoma — calcitonin-secreting, RET/MEN2-related, not radioiodine-avid — mandating RET testing, genetic counselling, central node dissection and lifelong calcitonin/CEA surveillance rather than the DTC pathway above. [13]