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A 22-year-old woman presents with a 2cm smooth, fluctuant, painless swelling just to the left of the midline at the level of the hyoid bone. It moves upward when she swallows water and when she protrudes her tongue. TFTs are normal. Ultrasound confirms a cystic lesion.
Questions
a) What is the diagnosis and which two clinical signs confirm it? (2 marks)
Diagnosis: Thyroglossal duct cyst.
Two confirming signs: (1) moves upward on swallowing (the tract attaches to the larynx, which moves on swallowing), (2) moves upward on tongue protrusion (the tract connects to the foramen caecum at the tongue base). This second sign distinguishes it from a thyroid nodule (which moves on swallowing but NOT on tongue protrusion).
b) What is the standard surgical treatment, and why is this specific procedure necessary? (3 marks)
Sistrunk procedure: excision of the cyst + the entire thyroglossal tract + the central portion of the hyoid bone.
This is necessary because the thyroglossal duct passes through the hyoid bone. Simple excision of the cyst alone leaves the tract behind, leading to 50% recurrence. The Sistrunk procedure (removing the tract and central hyoid) reduces recurrence to under 5%.
c) What pre-operative check is essential before surgery, and why? (2 marks)
Confirm normal thyroid position and function (TFTs + ultrasound). The swelling could be ectopic thyroid tissue (thyroid tissue that failed to descend normally). If it is the patient's ONLY thyroid tissue, removing it would cause hypothyroidism requiring lifelong thyroxine replacement.
d) How would the management differ if this were a 55-year-old smoker with a hard, fixed, painless lateral neck mass? (3 marks)
In an adult over 40, a neck lump is malignancy until proven otherwise. Management:
- Ultrasound + FNA of the mass (NOT trial of antibiotics or observation).
- If FNA shows metastatic SCC: panendoscopy (examine oral cavity, pharynx, larynx) with directed biopsies to find the primary tumour.
- Treatment depends on primary site (e.g., oral cavity: surgery + neck dissection + radiotherapy; oropharynx: chemoradiotherapy).