A 48-year-old man presents with a painless level II neck node. FNAC reveals metastatic squamous cell carcinoma. After thorough clinical examination and panendoscopy, no primary tumour is found. PET-CT is also negative for the primary. Which site is the most common occult primary in this scenario?
- A Floor of the mouth
- B Nasopharynx
- C Tonsillar fossa and base of tongue (Waldeyer's ring) ✓
- D Piriform sinus
Correct answer: C. Tonsillar fossa and base of tongue (Waldeyer's ring)
Explanation
In patients with cervical metastatic squamous cell carcinoma and an unknown primary tumour, Waldeyer's ring (especially the palatine tonsil and base of tongue) is the most common occult primary site, accounting for approximately 40-50% of cases. Many are HPV-positive oropharyngeal cancers. Bilateral tonsillectomy and directed biopsies of the tongue base are included in the diagnostic workup. PET-CT has improved detection but small cryptic tonsil primaries can still be missed.
Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.