ENT Liu Knowledge Base Head & neck tumours · physician reviewed
Head and Neck Cancer of Unknown Primary · Symptoms & diagnosis

How is a hidden primary tumour found?

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

After FNA, contrast CT/MRI and FDG PET-CT, the standard next step is examination under anaesthesia with directed biopsies, bilateral palatine tonsillectomy and, increasingly, transoral robotic (TORS) mucosectomy of the base of tongue. These procedures find a small primary in a substantial proportion of patients previously labelled "unknown".

In detail

Identifying the primary allows the radiotherapy field to be narrowed and may permit surgical resection, reducing long-term dry mouth and swallowing difficulty. In EBV-endemic regions the nasopharynx must be examined and imaged with MRI as well.

What this means in practice: this answer is part of the “Symptoms & diagnosis” 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. NCCN Guidelines for Patients: Head and Neck Cancers National Comprehensive Cancer Network · 2025
  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.

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.