Head and Neck Reconstruction and Oncology
What this domain tests
Staging and margin principles, neck level anatomy, and matching a defect to a reliable flap. Stems typically present a resected defect and ask for the best reconstruction or the correct oncological step.
Oncology principles
- Squamous cell carcinoma margins: aim for 5 mm; a margin under 1 mm is positive. Adjuvant radiotherapy is indicated for positive or close margins, extranodal extension, perineural or lymphovascular invasion, T3/T4 disease and multiple involved nodes. AJCC 8th edition incorporates depth of invasion and extranodal extension.
- Sentinel node biopsy is used for early oral cavity tumours with no clinical nodes (depth above roughly 3–4 mm) and for head and neck melanoma.
- Melanoma margins by Breslow: in situ 0.5–1 cm; up to 1 mm, 1 cm; 1–2 mm, 1–2 cm; over 2 mm, 2 cm. Sentinel node biopsy for lesions above 0.8 mm or thinner with ulceration.
Neck levels
I submental and submandibular; II upper jugular; III mid jugular; IV lower jugular; V posterior triangle (spinal accessory nerve); VI anterior compartment (recurrent laryngeal nerve, parathyroids); VII superior mediastinum. Oral cavity cN0 dissection is levels I–III.
Reconstruction
- Local: nasolabial, bilobed, paramedian forehead for nasal defects.
- Regional: pectoralis major myocutaneous flap (type V, thoracoacromial pedicle) for oral cavity salvage; deltopectoral; submental island; supraclavicular.
- Free: radial forearm for thin oral lining, ALT for bulk, fibula for mandible over 6 cm, jejunum for pharyngo-oesophageal defects.
- Parotid: pleomorphic adenoma needs superficial parotidectomy with a cuff - enucleation causes recurrence. Adenoid cystic carcinoma spreads perineurally and recurs late.
Worked example
A 3 cm T2 squamous cell carcinoma of the lateral tongue with a clinically negative neck. Reasoning: wide excision with 1 cm margins, ipsilateral selective neck dissection levels I–III (or sentinel node biopsy), and reconstruction with a radial forearm free flap for pliable lining that preserves tongue mobility. If histology shows extranodal extension or a close margin, add adjuvant radiotherapy and document the multidisciplinary decision.
Traps
- Enucleating a pleomorphic adenoma.
- Omitting level VI in the appropriate thyroid or laryngeal primary.
- Planning a fibula for mandible without dental rehabilitation.
- Attempting free tissue transfer in a vessel-depleted neck without a vein graft or arteriovenous loop plan.
- Treating a close margin as adequate in a high-grade tumour.