Thyroid Nodules & Goitre
Summary
Thyroid nodules are extremely common, detected in up to 50% of the adult population by ultrasound. The vast majority (>95%) are benign (colloid cysts, adenomas, thyroiditis). The clinical challenge is to identify the small minority that represent Thyroid Cancer without subjecting thousands of patients to unnecessary surgery. [1,2]
Key Facts
- Incidentaloma: Most nodules are found incidentally on CT/MRI done for other reasons.
- Function: Most nodules are non-functioning (euthyroid). A "Hot Nodule" (Toxic Adenoma) causes hyperthyroidism but is almost never cancerous.
- Goitre: Generalised enlargement of the gland. Can be diffuse (Graves') or multinodular (MNG). Retrosternal goitres can compress the trachea.
Clinical Pearls
Pemberton's Sign: Used to detect retrosternal goitre with thoracic inlet obstruction. Ask the patient to raise both arms above their head (touching ears) for 1 minute.
- Positive: Facial congestion (plethora), cyanosis, or inspiratory stridor.
- Mechanism: The goitre is lifted into the thoracic inlet, compressing the great veins (SVC obstruction) "like a cork in a bottle".
The "Follicular" Dilemma: Fine Needle Aspiration (FNA) CANNOT distinguish between Follicular Adenoma (Benign) and Follicular Carcinoma (Malignant). Why? Because the only difference is capsular or vascular invasion, which you cannot see on a cytology smear. Therefore, all "Follicular Neoplasms" (Thy3f) must be surgically removed (diagnostic hemithyroidectomy) to check the capsule.
Risk Factors for Malignancy
- Age: less than 20 or >60 years.
- Gender: Male (Nodules are rarer in men, so proportionately more likely to be cancer).
- History: Head/Neck irradiation in childhood. Family history of MEN2 (Medullary Ca).
- Characteristics: Hard, fixed, associated lymphadenopathy.
Nodule Types
- Colloid Nodule: Overgrowth of normal tissue. Benign.
- Cyst: Degeneration / haemorrhage.
- Adenoma: Benign neoplasm.
- Carcinoma:
- Papillary (80%): Young. Excellent prognosis. Lymphatic spread.
- Follicular (10%): Haematogenous spread (Bone/Lung).
- Medullary: Parafollicular C-Cells (Calcitonin).
- Anaplastic: Elderly. Very aggressive. Fatal.
History
Signs
- Inspection: Observe swallowing.
- Palpation: Stand behind patient. Palpate isthmus and lobes.
- Percussion: Retrosternal dullness?
- Pemberton's Test.
1. Thyroid Function Tests (TSH)
- Suppressed TSH: Suggests "Hot Nodule". Low cancer risk. Perform Isotope Scan.
- Normal/High TSH: Proceed to Ultrasound.
2. Ultrasound (U Classification)
- The BTA (British Thyroid Association) grading:
- U1: Normal.
- U2: Benign (Cystic, Spongiform, Halo). -> Observe.
- U3: Indeterminate. -> FNA.
- U4: Suspicious (Solid, Hypoechoic). -> FNA.
- U5: Malignant (Irregular shape, Microcalcification). -> FNA.
3. Fine Needle Aspiration (Thy Classification)
- Cytology grading:
- Thy1: Non-diagnostic (Not enough cells). Repeat.
- Thy2: Benign. Discharge.
- Thy3a: Atypia. Repeat.
- Thy3f: Follicular Neoplasm. Surgery.
- Thy4: Suspicious. MDT discussion.
- Thy5: Malignant. Surgery.
Management Algorithm
THYROID NODULE
↓
CHECK TSH
┌───────────┴───────────┐
LOW NORMAL/HIGH
(Hyperthyroid) (Euthyroid)
↓ ↓
ISOTOPE SCAN ULTRASOUND
(Hot vs Cold) (Assign U Score)
↓ ↓
HOT NODULE U3 / U4 / U5
(Toxic Adenoma) ↓
↓ DO FNA
RX: RADIOIODINE ↓
OR SURGERY ┌───────┴───────┐
BENIGN MALIG/SUSP
(Thy2) (Thy3f/4/5)
↓ ↓
DISCHARGE SURGERY
(Unless huge)
Surgical Options
- Hemithyroidectomy: Diagnostic (for Thy3f) or Therapeutic (for small cancers). Minimal complication risk. Patient stays euthyroid.
- Total Thyroidectomy: For large cancers (>4cm), bilateral disease, or Graves'. Requires lifelong Thyroxine (Levothyroxine). Higher risk of Hypocalcaemia.
- Radioiodine (I-131): Post-op ablation for remnant cancer tissue (Papillary/Follicular).
Surgical Complications
- Recurrent Laryngeal Nerve Palsy: Hoarse voice (unilateral) or Airway obstruction (bilateral).
- Hypocalcaemia: Damage to Parathyroid glands. (Transient in 20%, Permanent in 1-2%).
- Bleeding: Neck haematoma can compress airway -> Emergency (Requires opening the wound at bedside).
- Papillary/Follicular Ca: Excellent (>90% 10-year survival). Treated essentially as a chronic disease.
- Anaplastic Ca: Dismal (less than 6 months survival). Often presents with rapid airway obstruction requiring tracheostomy.
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| Thyroid Cancer | BTA (British Thyroid Assoc) | U-score and Thy-score system. MDT approach. |
| Nodule Mgmt | ATA (American Thyroid Assoc) | Size thresholds for biopsy (>1cm). |
Landmark Evidence
1. Active Surveillance
- Recent studies from Japan suggest small papillary microcarcinomas (less than 1cm) can be safely watched without surgery, as they rarely progress.
What is a thyroid nodule?
It is a lump in the thyroid gland (in the neck). It is like a mole on the skin - very common, and usually harmless.
Do I have cancer?
It is very unlikely (only 1 in 20 nodules are cancer). We do an ultrasound and a needle test to be sure. Even if it is cancer, thyroid cancer is usually very curable.
What is the needle test?
It is a tiny needle (like a blood test) put into the lump to suck out some cells. It takes 2 minutes.
Will I need tablets forever?
If we remove half the thyroid, the other half acts as a spare and works fine. If we remove the whole gland, you will need to take a daily hormone tablet (Thyroxine) for life to replace what the gland did.
Primary Sources
- Perros P, et al. Guidelines for the management of thyroid cancer. Clin Endocrinol (Oxf). 2014. (BTA Guidelines).
- Haugen BR, et al. 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer. Thyroid. 2016.
- Cibas ES, Ali SZ. The 2017 Bethesda System for Reporting Thyroid Cytopathology. Thyroid. 2017.
Common Exam Questions
- Diagnosis: "FNA result Thy3f?"
- Answer: Follicular Neoplasm. Next step is Diagnostic Hemithyroidectomy (not repeat FNA).
- Sign: "Pemberton's Sign positive?"
- Answer: Retrosternal goitre obstructing thoracic inlet.
- Anatomy: "Nerve at risk?"
- Answer: Recurrent Laryngeal Nerve.
- Investigation: "First test?"
- Answer: TSH.
Viva Points
- Medullary Cancer: Associated with MEN2 syndrome (RET proto-oncogene). Always check Calcitonin levels if suspected. Check for Phaeochromocytoma before operating (anaesthetic risk).
- Orphan Annie Eyes: Histological appearance of Papillary Carcinoma nuclei (clear/empty).
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.