Unknown/Occult Primary Cancers (CUP) of Head & Neck: Imaging


  • Identify suspicious areas to direct biopsies
  • Are cervical metastases resectable? (Ultrasound / CT)
  • Exclude pulmonary metastases or lung primary (CXR / CT)

Symptoms related to upper aerodigestive tract, prior skin cancers

  • Initially select only one of CT / MRI / PET (Law of diminishing returns with >1 imaging modality)
  • CT / MRI / CT+MRI detect primary tumour in <25% of cases
  • When suspicious imaging findings are used to direct biopsies, finding a primary increases to 60%
  • Imaging should be done prior to examination under anaesthesia (EUA) and biopsies as trauma may cause false +ves
  • Contrast enhanced CT: Skull base to clavicles (May include lungs to exclude lung primary or metastases)
  • MRI
    • Skull base to clavicles
    • Better soft tissue resolution than CT
  • PET
    • Detects tumours of >5mm
    • False +ves in oropharynx
    • Expensive
    • Availability may be limited

Index: Clinical Practice Guidelines for CUP

Resource Appropriate CUP Guideline Scenarios