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Q1: Approach to a thyroid nodule (2 min)
Examiner: A 50-year-old woman is found to have a thyroid nodule. Walk me through your approach.
Expected answer:
- Begin with a focused HISTORY: childhood neck irradiation, family history of thyroid cancer or MEN-2, growth rate, compressive or voice symptoms; examine for consistency, fixation and cervical lymphadenopathy.
- FIRST blood test is a SERUM TSH. A normal/raised TSH proceeds to ULTRASOUND risk-stratification (ACR TI-RADS); a SUPPRESSED TSH suggests a hot nodule (low malignancy risk) assessed by radionuclide scintigraphy.
- Risk-stratify the nodule on ultrasound: solid, hypoechoic, taller-than-wide, irregular margins and microcalcifications are suspicious features.
- BIOPSY selectively: ultrasound-guided FNA with BETHESDA cytology (I nondiagnostic to VI malignant) only for high-TI-RADS nodules — most nodules are benign and can be observed.
Q2: The four thyroid cancers (3 min)
Examiner: Classify thyroid malignancies and give the distinguishing feature of each.
Expected answer:
- PAPILLARY (80 to 85 percent): commonest, excellent prognosis, LYMPHATIC spread; psammoma bodies, nuclear grooves and pseudoinclusions; BRAF V600E driver; treated by thyroidectomy plus or minus RAI.
- FOLLICULAR (5 to 10 percent): HAEMATOGENOUS spread to bone and lung; defined by CAPSULAR and VASCULAR INVASION (cannot be diagnosed on FNA); RAS and PAX8-PPAR-gamma; takes up RAI.
- MEDULLARY (2 to 3 percent): PARAFOLLICULAR C-cell origin; CALCITONIN and amyloid stroma; RET mutation, MEN-2; surgery and genetic testing; NO response to RAI.
- ANAPLASTIC (1 to 2 percent): UNDIFFERENTIATED, older patients, dedifferentiation of a prior cancer (TP53, TERT); very aggressive, largely PALLIATIVE; accounts for most thyroid cancer deaths.
Q3: Bethesda and management (3 min)
Examiner: A nodule reports Bethesda category III. What does that mean and how do you proceed?
Expected answer:
- Bethesda III = ATYPIA of undetermined significance / follicular lesion of undetermined significance; malignancy risk roughly 10 to 30 percent.
- Proceed with MOLECULAR TESTING (gene-expression classifier or sequencing panel such as Afirma, Thyroseq) to refine risk; repeat FNA or diagnostic lobectomy if clinical/sonographic suspicion is high.
- Map to the other categories: I nondiagnostic (repeat FNA), II benign (observe), IV follicular neoplasm (lobectomy), V suspicious (thyroidectomy), VI malignant (thyroidectomy).
- Confirmed differentiated cancer: thyroidectomy (lobectomy for low-risk, total for higher-risk), RAI ablation for intermediate/high-risk, and TSH suppression with thyroglobulin surveillance.
Q4: Medullary cancer and MEN-2 (2 min)
Examiner: How would you manage a newly diagnosed medullary thyroid cancer?
Expected answer:
- Confirm with raised CALCITONIN and amyloid-stroma cytology; measure CEA as a baseline tumour marker.
- BEFORE surgery, EXCLUDE a PHAEOCHROMOCYTOMA (plasma or 24-hour urine fractionated metanephrines) — an unrecognised phaeo causes a lethal intra-operative hypertensive crisis.
- Surgery: TOTAL THYROIDECTOMY with central and lateral neck dissection; screen calcium for hyperparathyroidism (MEN-2A).
- RET genetic testing and family counselling; known RET carriers undergo PROPHYLACTIC thyroidectomy (timing by mutation risk class). Medullary cancer does NOT respond to RAI; advanced disease uses cabozantinib or vandetanib.
Q5: Surgical complications and prognosis (2 min)
Examiner: What are the complications of thyroid surgery, and what is the prognosis?
Expected answer:
- Early: RECURRENT LARYNGEAL NERVE injury (hoarseness — assess vocal cords pre- and post-op), HYPOPARATHYROIDISM (hypocalcaemia — monitor and replace calcium and calcitriol), bleeding or neck haematoma (airway emergency).
- Long-term RAI: sialadenitis, dry mouth, small secondary malignancy risk; chronic TSH suppression causes osteoporosis and atrial fibrillation.
- Prognosis: differentiated cancer EXCELLENT (5-year survival over 98 percent for localised papillary); medullary variable by stage; anaplastic almost uniformly fatal within months.
- Recurrence surveillance for differentiated cancer is with SERIAL THYROGLOBULIN (only reliable after complete thyroid ablation and if anti-thyroglobulin antibodies are absent) and neck ultrasound.