Makindo Medical Notes

Related Subjects: |Thyrotoxicosis and Hyperthyroidism |Thyroid Storm - Thyrotoxic crisis |Graves Disease (Thyrotoxicosis) |Amiodarone and Thyroid disease |Thyroid Surgery (Thyroidectomy) |Hypothyroidism |Hashimoto's thyroiditis |DeQuervain's thyroiditis |Subacute Thyroiditis |Thyroid nodule |Congenital Hypothyroidism |Thyroid Function Tests and antibodies |Post partum thyroiditis |Sick Euthyroid Syndrome |Thyroid Exam (OSCE) |Thyroid Gland anatomy and Physiology |Thyroid Cancer

📈 The incidence of thyroid cancer — the most common endocrine malignancy — has risen sharply over the last 50 years. Despite this, most cases are detected early and have a good prognosis if not metastatic.

📖 About

• 🔎 Usually presents as a palpable thyroid nodule, but only 1 in 25 nodules are malignant.
• 👩 More common in women, though men tend to have a worse prognosis.
• ⏳ Peak incidence: 40–50 years of age.

🧬 Cancer Classifications

• Broadly divided into differentiated (papillary, follicular, Hurthle cell) and undifferentiated (anaplastic), or by follicular vs non-follicular origin.
• Most patients present with localised disease. About 10% have distant metastases at diagnosis; cervical lymph node spread is common.
• FNA biopsy is the gold standard investigation for any thyroid nodule.

• 🌸 Papillary Thyroid Carcinoma (85–90%):
  • Commonest type, affects younger patients.
  • Excellent prognosis.
  • Histology: laminated calcified Psammoma bodies.
  • Risk factor: prior neck radiation exposure.
  • Spreads to cervical lymph nodes.
• 🍂 Follicular Thyroid Carcinoma (<10%):
  • Middle-aged women (40–50 years).
  • Spreads haematogenously to bone, lung, liver, brain.
  • Histology cannot distinguish adenoma vs carcinoma → requires hemithyroidectomy for diagnosis.
  • Treatment: completion thyroidectomy + radioactive iodine ablation if carcinoma confirmed.
• 🧪 Hurthle Cell Carcinoma:
  • A rare, more aggressive variant of follicular carcinoma.
  • Histology: Hurthle cells with abundant eosinophilic, granular cytoplasm (due to altered mitochondria).
  • Spreads to lung, bone, brain.
• ⚡ Anaplastic (Undifferentiated) Thyroid Carcinoma:
  • Seen in elderly, extremely aggressive.
  • Often inoperable at diagnosis.
  • Very poor prognosis, survival usually months.
• 🧬 Medullary Thyroid Carcinoma (3%):
  • Arises from parafollicular C-cells.
  • Produces calcitonin and often associated with MEN2 syndromes.
  • Histology may show amyloid stroma.
  • Treated surgically; radiotherapy may be used. Radioiodine is not effective.

🔬 Investigations

• 🩸 Bloods: FBC, U&E, Ca, LFTs, TFTs.
• 📊 Thyroglobulin: sensitive tumour marker for differentiated cancers (papillary/follicular).
• 🔎 FNA biopsy: standard for any thyroid nodule.
• ☢️ Radioactive iodine uptake/whole body scans for staging and recurrence monitoring.

🛠️ General Management

• ✂️ Surgery: lobectomy, near-total or total thyroidectomy (depending on pathology).
• ☢️ Post-op radioactive iodine ablation for differentiated cancers.
• 💊 Long-term thyroxine replacement to maintain normal thyroid function and TSH suppression (reduces tumour stimulation).
• 🔎 Surveillance:
  • Detectable thyroglobulin → recurrence or metastases (prompt whole-body I-131 scan).
  • Neck US and clinical follow-up for local recurrence.
• ⚠️ Red flag features: elderly patient, hard fixed nodule, stridor, hoarseness (possible recurrent laryngeal nerve involvement).