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Head and Neck Cancer of Unknown Primary · Understanding the disease

What is head and neck cancer of unknown primary?

Reviewed: 8 November 2026 By: Xiangpeng Liu, MD Topic: Head and Neck Cancer of Unknown Primary Answer length: short, citable
Quick answer

Head and neck cancer of unknown primary means a malignant cervical lymph node is found but no primary tumour can be seen after the initial examination. In North America and Northern Europe this presentation has become more common because small HPV-positive tonsil or base-of-tongue cancers hide in crypts. p16/HPV and EBV testing on the node aspirate usually points to the tissue of origin.

In detail

A painless neck lump in an adult is cancer until proven otherwise. The work-up aims to find a hidden primary in the tonsil, base of tongue, nasopharynx, hypopharynx, thyroid, salivary gland or skin. When HPV-driven oropharyngeal cancer is common — as in the US, UK and Scandinavia — an HPV-positive, cystic upper-neck node with no visible lesion is now a recognisable clinical entity rather than a mystery.

Finding the primary changes treatment: it can allow a smaller radiation field, transoral surgical resection and less long-term toxicity. Modern work-up therefore adds PET-CT, p16 and HPV/EBV testing, examination under anaesthesia, palatine tonsillectomy and transoral robotic base-of-tongue mucosectomy to the traditional endoscopic evaluation.

What this means in practice: this answer is part of the “Understanding the disease” section of the Head and Neck Cancer of Unknown Primary topic. If you are comparing treatment options, also read how to compare a second opinion and which records to send.

Other common questions about head and neck cancer of unknown primary

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Sources for this answer

  1. HPV & Oropharyngeal Cancer US National Institute of Dental and Craniofacial Research · 2025 · About 70% of oropharyngeal cancers in the United States are HPV-positive.
  2. HPV Detection in Oropharyngeal Cancer: A Narrative Review PubMed Central / peer-reviewed review · 2025 · HPV-attributable fraction: ~71% US, ~52% UK, >60% Scandinavia, <20% Southern Europe, ~44% globally.
  3. NCCN Guidelines for Patients: Head and Neck Cancers National Comprehensive Cancer Network · 2025
  4. Head and Neck Cancers (patient information) US National Cancer Institute · 2025

Written and medically reviewed by Xiangpeng Liu, MD

Associate Chief Physician, ENT & Head/Neck Surgery · Chenzhou First People’s Hospital, Chenzhou, Hunan, China

Editorial policy & reviewer credentials · All sources

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Medical disclaimer: This knowledge base is general information for people researching head and neck tumours, not a diagnosis or treatment plan. It does not replace an examination by a qualified physician. Survival figures are population averages, not predictions for an individual. Treatment and cost estimates for China are illustrative only and must be confirmed in writing after your records have been reviewed. If you have a symptom lasting more than two to three weeks, see a doctor promptly.