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SU22.1-6 | Thyroid and Parathyroid Surgery — Graded Quiz
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A patient has a small midline neck swelling that moves both on swallowing and on protrusion of the tongue. Knowing the embryology of the thyroid, what is the most likely diagnosis?
Correct. The thyroid descends from the foramen caecum along the thyroglossal duct; a remnant produces a midline thyroglossal cyst that moves on swallowing and on tongue protrusion.
Thyroglossal cyst: midline, moves on swallowing AND tongue protrusion; arises from the thyroglossal duct (foramen caecum origin).
Movement on tongue protrusion (as well as swallowing) of a midline swelling is characteristic of a thyroglossal cyst, reflecting the thyroid's embryological descent.
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Which statement about the aetiopathogenesis of simple (non-toxic) goitre is correct?
Correct. Iodine deficiency reduces thyroid hormone output, raising TSH and driving compensatory hyperplasia (goitre); this is the classic cause of endemic goitre, and large goitres can cause pressure symptoms.
Endemic goitre: iodine deficiency → TSH-driven hyperplasia; large goitres cause pressure symptoms.
Iodine deficiency → low hormone → raised TSH → compensatory hyperplasia is the mechanism of endemic simple goitre. Large goitres may compress trachea/oesophagus.
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A solitary thyroid nodule is found in a patient whose serum TSH is SUPPRESSED. Which investigation is most appropriate to perform first, and why?
Correct. A suppressed TSH suggests an autonomously functioning nodule; a radionuclide scan identifies a hot nodule (rarely malignant) and is therefore done first in this specific situation.
Suppressed TSH → radionuclide scan first; normal/raised TSH → ultrasound + FNAC.
Only a SUPPRESSED TSH justifies a radionuclide scan first (to find a hot nodule). With a normal/raised TSH, proceed straight to ultrasound and FNAC.
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When an FNAC result is reported, which classification system is used to stratify the risk of malignancy of a thyroid nodule and guide management?
Correct. The Bethesda system categorises thyroid FNAC results into risk tiers (e.g. benign, follicular neoplasm, suspicious, malignant) that guide whether to observe, repeat, operate diagnostically, or proceed to cancer surgery.
Thyroid FNAC → Bethesda categories drive management decisions.
Thyroid FNAC is reported using the Bethesda system. Gleason is for prostate, Dukes for colorectal, Breslow for melanoma, Child–Pugh for liver disease.
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Which statement correctly contrasts the behaviour of papillary and follicular thyroid carcinoma?
Correct. Papillary carcinoma spreads mainly via lymphatics (cervical nodes) and is suggested by FNAC; follicular carcinoma spreads haematogenously (bone, lung) and requires histology (capsular/vascular invasion) for diagnosis. Both, being differentiated, take up radioiodine.
Papillary: lymphatic, psammoma bodies. Follicular: haematogenous, needs histology. Both differentiated → radioiodine.
Papillary = lymphatic spread, FNAC-suggestive; follicular = haematogenous spread, histology-dependent. Both differentiated cancers respond to radioiodine.
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Two days after total thyroidectomy a patient develops perioral tingling, paraesthesiae in the fingers, and a positive Chvostek's sign. What is the most likely cause?
Correct. Perioral and digital paraesthesiae with a positive Chvostek's sign after total thyroidectomy indicate hypocalcaemia from parathyroid injury/devascularisation (hypoparathyroidism).
Key thyroidectomy complications: recurrent laryngeal nerve injury (voice) and hypoparathyroidism (hypocalcaemia, Chvostek/Trousseau).
Post-thyroidectomy tetany/paraesthesiae with Chvostek's sign reflect hypocalcaemia from parathyroid damage. Recurrent laryngeal nerve injury causes hoarse voice/airway problems, not hypocalcaemia.
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Which statement about the applied anatomy of the parathyroid glands is correct?
Correct. There are usually four parathyroids on the posterior thyroid, supplied chiefly by the inferior thyroid artery; the superior pair arise from the fourth and the inferior pair from the third pharyngeal pouch (the inferior pair being more variable in position).
Four parathyroids; inferior thyroid artery supply; superior=4th pouch (constant), inferior=3rd pouch (variable).
Four glands, posterior thyroid surface, inferior thyroid artery supply; superior pair from 4th pouch (constant), inferior pair from 3rd pouch (variable, may descend with the thymus).
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A patient with primary hyperparathyroidism is to undergo surgery. Which principle correctly describes the sequence of diagnosis and localisation?
Correct. Diagnose primary hyperparathyroidism biochemically (high calcium with inappropriately raised PTH) before localising the adenoma; a scan never makes the diagnosis and surgery is not planned on imaging alone.
Biochemistry confirms primary HPT; imaging only localises. Never plan surgery on imaging alone.
Diagnose the parathyroid before you image it: biochemistry (high Ca + inappropriate PTH) first, then localisation. A normal/suppressed PTH with high calcium points elsewhere.
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