Introduction
Patients presenting with head and neck squamous cell carcinoma of unknown primary (HNSCCUP) pose a diagnostic conundrum. Cancer of unknown primary is defined as the “histological diagnosis of metastasis without the detection of a primary tumor”1. The cited incidence of HNSCCUP is between 2% to 5% of all head and neck squamous cell carcinoma (SCC)2,3.
When clinical examination and imaging have failed to identify a potential primary site, traditional further investigation of HNSCCUP comprises examination under anaesthetic (EUA), evaluation of all subsites of the head and neck and either targeted and/or random biopsies. The typical biopsy sites are nasopharynx, tonsils, tongue base, and piriform fossa, although there is considerable heterogeneity and little high level evidence exists to support this routine4,5.
The rationale for intensively searching for the primary site is as follows:
1. The majority of patients presenting with HNSCCUP will harbour primary sites in the head and neck6.
2. There may be prognostic and therapeutic benefits to finding the primary site, by being able to precisely target the primary site and reduce the morbidity of treatment7.
This systematic review identifies the indications and practice of oropharyngeal biopsy in HNSCCUP and focuses on the following:
1. Random versus direct biopsies
2. Management of the palatine tonsils
3. Management of the tongue base
4. Utility of surgical techniques