Transcervical ultrasound identifies primary tumor site of unknown primary head and neck squamous cell carcinoma.

H ead and neck squamous cell carcinomas (HNSCCs) of unknown primary site (UP) account for approximately 4% of HNSCCs. These cases have historically been subclinical tumors arising from the nasopharynx, hypopharynx, or oropharynx. In the era of human papillomavirus (HPV)–positive HNSCCs, the presence of HPV in cervical malignancy of UP has been strongly associated with oropharyngeal primary tumors. Tumors that are HPV– positive are typically small and arise from cryptic lingual and palatine lymphoid tissues, rendering primary tumor detection challenging. The traditional diagnostic paradigm for finding the primary tumor consists of a physical examination, fiber-optic laryngoscopy, and imaging. If these techniques are unsuccessful, operative examination under anesthesia is warranted, including direct laryngoscopy with ‘‘blind’’ biopsies directed at the nasopharynx, hypopharynx, oropharynx, larynx, and palatine and lingual tonsillectomy. Failure to identify the primary tumor site subsequently necessitates radiation of Waldeyer’s ring and concurrent chemotherapy. This report shows that transcervical ultrasound (US) can be used to localize oropharyngeal tumors. The study was reviewed and approved by the Greater Baltimore Medical Center Institutional Review Board.