Abstract
Most neoplastic causes of cervical lymphadenopathy are metastases from head and neck cancers. For physicians to treat cervical lymphadenopathy, basic knowledge for frequent sites and incidence rates of each primary head and neck cancer is required for appropriate diagnosis and disease control. In p16-positive oropharyngeal cancer（OPC）, it is important to note, that cervical metastasis may appear at any stage, even when the primary tumor is still small. It may present as a carcinoma of unknown primary（CUP）, and thorough endoscopic examination of the nasopharyngeal cavity, combined with the Modified Killian position, is recommended to identify the potential primary site. Fine needle aspiration of the lymph node may be conducted, if necessary, followed by a biopsy if suspected of malignant lymphoma. Cystic change is another known feature of p16-positive OPC metastasis to lymph nodes. Differential diagnosis include metastasis from thyroid papillary cancer, as well as benign lateral cyst, and differences in their MRI findings may provide hints for diagnosis.
For metastatic lymph nodes of thyroid papillary cancers, and squamous cell carcinomas of oral cancers and hypopharyngeal cancers, main stream of treatment is to perform selective neck dissection. On the other hand, that of nasopharyngeal cancer and p16 positive OPC is to perform chemoradiotherapy, in consistent with the primary lesion. In this session, diagnosis and treatment of CUP, its relationship with p16-positive OPC in particular, was discussed.
