A thyroid nodule is a discrete lesion within the thyroid gland, radiologically distinct from surrounding parenchyma.
Nodules are common (especially in women and older adults) 👍 and most are benign - but a small proportion are malignant 🚨.
In UK practice, management is guided by NICE Suspected Cancer (NG12), UK thyroid cancer guidance, and radiology risk stratification (e.g. U-classification / TI-RADS).
📊 Epidemiology
- Up to 50–60% of adults >60 years have nodules on ultrasound.
- ♀:♂ ≈ 4:1, but malignancy risk relatively higher in men.
- ~5% of palpable nodules are malignant.
🚨 NICE NG12 - When to Refer (2-Week Wait)
- Unexplained thyroid lump in a patient aged ≥18 years.
- Thyroid mass with associated cervical lymphadenopathy.
- Rapidly enlarging mass, especially with hoarseness (possible RLN involvement).
- Hard, irregular, fixed mass.
⚠️ Any persistent thyroid lump in an adult warrants urgent referral unless clearly benign.
Hoarseness + thyroid nodule = assume malignancy until proven otherwise.
🩺 Clinical Assessment
- Moves with swallowing ⬆️
- Check cervical lymph nodes
- Assess voice (recurrent laryngeal nerve)
- Symptoms of hyper- or hypothyroidism ⚖️
- Risk factors: childhood radiation ☢️, family history (MEN2, medullary Ca), age extremes
🧪 Initial Investigations (Primary & Secondary Care)
- TSH (first-line test)
- If TSH suppressed → consider radionuclide scan
- If TSH normal or raised → proceed to ultrasound
- Thyroid antibodies if autoimmune disease suspected
- Calcitonin only if medullary cancer suspected (family history MEN2)
🖥️ Ultrasound Risk Stratification (UK Practice)
| Ultrasound Feature |
Malignancy Risk |
| Solid, hypoechoic |
↑ Risk |
| Irregular margins |
↑ Risk |
| Microcalcifications |
↑ Risk |
| Taller-than-wide shape |
↑ Risk |
| Purely cystic |
Very low risk 👍 |
Suspicious nodules → FNA biopsy (fine needle aspiration) using the Bethesda reporting system.
🧬 FNA Cytology (Bethesda Classification)
| Bethesda Category |
Management |
| I - Non-diagnostic |
Repeat FNA |
| II - Benign |
Clinical + US follow-up |
| III/IV - Indeterminate |
Repeat FNA or diagnostic lobectomy |
| V - Suspicious |
Surgical management |
| VI - Malignant |
Definitive surgery |
☢️ Radionuclide Scan (If TSH Low)
- Hot nodule → autonomous, rarely malignant 👍
- Cold nodule → requires ultrasound + FNA risk assessment
📊 Common Causes & NICE-Aligned Management
| Cause |
Features |
Management (UK Practice) |
| 🪢 Benign Colloid Nodule |
Smooth, soft; benign FNA |
Reassure + repeat US if growth |
| 🔥 Toxic Adenoma |
Suppressed TSH; hot on scan |
Radioiodine or hemithyroidectomy |
| 🌸 Multinodular Goitre |
Multiple nodules; ± hyperthyroid |
Observe, radioiodine, or surgery if compressive |
| 🎗️ Papillary / Follicular Cancer |
Hard mass; suspicious US; positive FNA |
Hemithyroidectomy or total thyroidectomy ± radioactive iodine; lifelong levothyroxine |
| 🧪 Thyroiditis |
Tender gland (subacute) or autoimmune features |
NSAIDs / steroids (subacute); levothyroxine if hypothyroid |
| 💧 Thyroid Cyst |
Sudden swelling; cystic on US |
Aspiration ± surgery if recurrent |
⚕️ Management Principles
- Benign nodules → monitor unless symptomatic.
- Suspicious/malignant → surgery via MDT decision.
- Autonomous nodules → treat hyperthyroidism.
- Large goitre with compression → surgical referral.
- All cancer cases managed via specialist endocrine MDT.
📅 Follow-Up
- Repeat ultrasound at 6–12 months if benign but suspicious features.
- Monitor TFTs.
- Post-thyroid cancer: thyroglobulin monitoring ± imaging.
📌 Key Clinical Pearls
- TSH is the first test in any thyroid nodule.
- Low TSH → radionuclide scan.
- Normal/high TSH → ultrasound + FNA.
- Hoarseness + hard thyroid lump = urgent referral 🚨.
- Most nodules are benign - risk stratify, don’t overoperate.
📚 References
- NICE NG12 - Suspected cancer: recognition and referral.
- British Thyroid Association Guidelines (latest update).
- ATA Guidelines for Thyroid Nodules & Differentiated Thyroid Cancer.
- Bethesda System for Reporting Thyroid Cytopathology.
