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Thyroid nodule and thyroid cancer
For a thyroid nodule the first test is TSH: a "hot" nodule with a low TSH is almost never malignant; otherwise ultrasound decides whether to aspirate, and cytology by the Bethesda system decides whether to operate.
Why it matters in the exam
Questions start with the order of work-up: TSH first, a scan only when TSH is low, and ultrasound, whose features (hypo-echogenicity, irregular margins, microcalcifications, "taller-than-wide" shape) and size decide on fine-needle aspiration (FNA). Then you must know what to do in each Bethesda category — from non-diagnostic to definitely malignant — and why molecular testing or lobectomy is used in the intermediate categories.
The second part is the cancer types: papillary (most common, spreads to lymph nodes, good prognosis), follicular (spreads by blood; cannot be diagnosed by FNA because the diagnosis requires capsular or vascular invasion), medullary (from C cells, secretes calcitonin, linked to RET and MEN2, and does not respond to radioactive iodine) and anaplastic (older patient, rapidly growing mass, poor prognosis). Candidates are also asked about surgical complications — recurrent laryngeal nerve injury (hoarseness), hypocalcaemia after total thyroidectomy, and neck haematoma compressing the airway.
Key points
- TSH first; low TSH — scan, and a hot nodule is not aspirated.
- Ultrasound decides on aspiration: high or intermediate suspicion — FNA from 1 cm.
- Bethesda II — follow-up; III–IV — repeat, molecular testing or lobectomy; V–VI — surgery.
- Papillary — lymph; follicular — blood; medullary — calcitonin, RET and MEN2; anaplastic — older patient and rapid growth.
- Surgical complications: recurrent nerve (hoarseness), hypocalcaemia, haematoma compressing the airway.
Summary table
| Type | Features | Spread and markers | Treatment |
|---|---|---|---|
| Papillary | Most common; linked to childhood radiation | Cervical lymph nodes; Tg for follow-up | Lobectomy for a low-risk 1–4 cm tumour; total thyroidectomy above 4 cm or with spread; iodine by risk |
| Follicular | Diagnosed only on histology (capsular or vascular invasion) | Blood-borne — bone and lungs | Diagnostic lobectomy; total thyroidectomy and iodine for invasive disease |
| Medullary | From C cells; RET and MEN2 | Calcitonin and CEA | Total thyroidectomy and central neck dissection; exclude phaeochromocytoma before surgery; iodine is not effective |
| Anaplastic | Older patient, rapidly growing mass, tracheal compression | Rapid local spread | Airway, BRAF testing and targeted therapy; poor prognosis |
| "Hot" nodule | Low TSH, uptake on scan | Almost always benign | No FNA; treat the hyperthyroidism |
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Sources
- American Thyroid Association guidelines for adult patients with thyroid nodules and differentiated thyroid cancer, 2015 — Evaluation of nodules, FNA criteria and initial surgery
- The Bethesda System for Reporting Thyroid Cytopathology, 3rd edition (2023) — Diagnostic categories and recommended management
- Sabiston Textbook of Surgery, 21st edition (2022) — Thyroid
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.