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Neck metastasis from an unknown primary

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Sometimes cancer is found in a neck lymph node before the tumour it came from; doctors then search the throat to find the hidden origin.

Updated

What it is

Squamous cell carcinoma in a neck lymph node with no primary tumour found after a careful search is called an occult or unknown primary. Upper neck nodes usually come from a head and neck primary, often small and hidden in the tonsil, base of tongue or nasopharynx; lower neck nodes can also come from the oesophagus, lung or genitourinary tract. The order of the workup matters: open surgery of the node is done only after the upper aerodigestive tract has been carefully examined.

Structure

  • Waldeyer's ring sites: tonsils, base of tongue, nasopharynx (adenoid area).
  • Hypopharynx: pyriform sinus.
  • Upper neck nodes: drainage of oral cavity, pharynx and larynx.
  • Lower neck and supraclavicular nodes: drainage also from chest and abdomen.

Step by step

  1. Full ENT exam: mouth, oropharynx, palpation of the base of tongue, and flexible endoscopy of nasopharynx, larynx and hypopharynx.
  2. Fine-needle aspiration of the node, with p16/HPV and, if a nasopharyngeal origin is suspected, EBV testing.
  3. Imaging of the neck (MRI preferred over CT for soft tissue); PET can help locate the primary.
  4. Search for distant metastases (lung, liver, bone), because they change treatment.
  5. Examination under anaesthesia with biopsies of nasopharynx, base of tongue, tonsil and pyriform sinus when no primary is seen.
  6. Open biopsy or excision of the node only after the primary has been carefully searched for.

In clinical practice

  • Treatment is radiotherapy and/or neck dissection, directed by the specialist team; fields include the likely hidden sites.
  • Thyroid function is checked before and after neck radiation because hypothyroidism is common afterwards.
  • Patients in whom the primary appears later have worse survival than those in whom it stays hidden.
  • In general practice most neck nodes are benign; malignancy is about 0.4% under 40 years and about 4% over 40 in primary care series, so age and risk factors decide urgency.

Next step / Initial management

  • In an adult with a persistent, firm, painless neck lump and no infection, request a blood count only if it does not delay referral; do not give repeated antibiotic courses.
  • Do not cut out or open-biopsy the node in primary care.
  • Refer urgently (same week) to otolaryngology or head and neck surgery for endoscopy and fine-needle aspiration; mention tobacco, alcohol and duration in the referral.
  • If the lump is supraclavicular or there is weight loss or night sweats, also consider lymphoma, lung and digestive tract causes and say so in the referral.

Test yourself

Think of the answer, then tap the question to see it.

Which three sites most often hide the primary of a cervical squamous cell metastasis?

The tonsil, the base of tongue and the nasopharynx, all part of Waldeyer's ring; the pyriform sinus is also sampled.

A neck node aspirate shows p16-positive squamous cell carcinoma. Where is the primary most likely?

In the oropharynx (tonsil or base of tongue), because p16 is a marker of HPV-related oropharyngeal cancer.

Why should an excisional biopsy of a suspicious neck node wait?

Because the aerodigestive tract must be examined first; the node may be a metastasis and the primary should be found and the treatment planned before open neck surgery.

What does a positive EBV test in a neck node aspirate suggest?

A nasopharyngeal carcinoma; it calls for a detailed examination of the nasopharynx.

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Educational content; it does not replace a medical assessment and is not a clinical instruction. For a real case, follow current guidelines and specialist advice.

Sources: Metastatic Squamous Neck Cancer With Occult Primary Treatment (PDQ), Health Professional Version (National Cancer Institute (NIH), 2025); Lymphadenopathy (StatPearls (NCBI Bookshelf), 2026); Nasopharyngeal Cancer (StatPearls (NCBI Bookshelf), 2024); Oropharyngeal Squamous Cell Carcinoma (StatPearls (NCBI Bookshelf), 2023).

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