A p16-Positive Level II Neck Node with a Suspected Tonsillar Primary
A 61-year-old man presents with a 4 cm right level II neck mass present for 10 weeks. He has no pain, dysphagia or hoarseness, and no significant smoking history. Examination shows a firm, mobile node; the oropharynx is crowded, with a prominent right tonsil but no visible ulceration, and the larynx is normal on flexible nasendoscopy. Fine-needle aspiration shows poorly differentiated squamous cell carcinoma, p16 positive on immunohistochemistry. Contrast CT shows a 4.1 cm right level II node with a necrotic centre, no contralateral nodes, and no distant disease. PET-CT shows intense uptake in the right tonsil and the node only. He asks why the tonsil cannot simply be watched and the neck treated with chemoradiotherapy.
1. What is the next diagnostic step, and why is it necessary when PET already points to the tonsil?
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Next step
- Examination under anaesthesia with panendoscopy, ipsilateral tonsillectomy (not just biopsy) and multiple base-of-tongue biopsies, plus directed biopsies of any PET-avid site.
- Send tissue for HPV testing by p16 immunohistochemistry plus HPV DNA or RNA, since p16 can be upregulated by non-HPV causes, particularly in non-smokers with unusual histology.
Why PET is not enough
- PET uptake in the tonsil is common and can reflect physiological lymphoid tissue or inflammation; it localises but does not histologically confirm the primary.
- Finding the primary allows targeted treatment: transoral robotic surgery or radiotherapy to a defined volume rather than an unknown-primary approach, which would otherwise irradiate the whole oropharynx and often both necks.
- It also excludes synchronous second primaries, which occur in about 5–10% of head and neck cancer patients and change the treatment plan.
- Tonsillectomy is preferred to superficial biopsy because HPV-related carcinoma often sits in the crypts and a surface biopsy can be negative.
2. Assuming the tonsillectomy confirms HPV-positive tonsillar carcinoma, how would you counsel him about treatment options and the reason the neck cannot be treated alone?
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Staging and principles
- This is HPV-mediated oropharyngeal carcinoma with a single ipsilateral node 4.1 cm, i.e. T0 N1 (or N2 depending on extranodal extension status) under the HPV-specific staging system, which has a much better prognosis than HPV-negative disease.
- Treat the primary site and the neck together. The tonsil is drained by the neck node; treating only the neck leaves an untreated primary that will progress and can seed new metastases.
- Assess extranodal extension on imaging and pathology, as it upstages disease and influences adjuvant treatment.
Options
- Primary surgery: transoral resection of the tonsil and primary neck dissection, with adjuvant radiotherapy or chemoradiotherapy if margins are close, extranodal extension is present, or multiple nodes are involved.
- Primary (chemo)radiotherapy to the oropharynx and neck, reserving surgery for salvage.
- De-escalation trials are reasonable in HPV-positive disease but should be discussed as trials, not standard care.
- Emphasise that HPV-positive disease has excellent outcomes (roughly 85–90% three-year survival in this stage) but still requires curative-intent treatment; observation is not an option.
3. Two weeks after completing chemoradiotherapy he develops a 3 cm firm, tender mass in the irradiated neck with fever. How do you evaluate this?
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Differential
- Expected acute radiation mucositis and lymphadenitis are common, but a new tender mass with fever must be assumed to be an abscess or necrotic node until excluded.
- Consider tumour progression or a second primary, though this is early.
Evaluation
- Examine the neck and oropharynx, check for trismus, dental sepsis and skin breakdown; mark and measure the mass.
- Urgent contrast CT neck with ultrasound correlation; if a fluid collection is present, ultrasound-guided aspiration for Gram stain, culture and cytology.
- Blood cultures and full blood count; assess swallowing and nutrition, as aspiration can mimic fever.
Management
- If an abscess is confirmed, drain it (usually ultrasound-guided) and start antibiotics covering oral flora and staphylococci; avoid radical neck dissection in the acute irradiated field.
- If cytology shows persistent viable carcinoma at this stage, it is too early to declare treatment failure; re-image at 12 weeks with PET-CT and discuss at multidisciplinary team.
- Do not start empirical chemotherapy or further radiotherapy without tissue and imaging confirmation.