Diagnostic approaches to carcinoma of unknown primary of the head and neck.

Squamous cell carcinoma in cervical lymph nodes arising from an undetected primary tumour, termed carcinoma of unknown primary (SCCUP), is a well-recognized clinical presentation within head and neck oncology. SCCUP is a common presentation for patients with human papillomavirus-mediated oropharyngeal cancer (HPV + OPSCC), as patients with HPV + OPSCC often present with smaller primary tumours and early nodal metastasis. Meticulous work-up of the SCCUP patient is central to the management of these patients as identification of the primary site improves overall survival and allows for definitive oncologic resection or more focused radiation when indicated. This review summarizes the comprehensive diagnostic approach to the SCCUP patient, including history and physical examination, methods of biopsy of the cervical lymph node, imaging modalities and intraoperative methods to localize the unknown primary. Novel techniques such as transcervical ultrasound of the oropharynx, narrow band imaging and diagnostic transoral robotic surgery are also discussed.