Cystic cervical nodal metastases are specific and easily recognizable manifestation of a subset of head and neck squamous cell carcinomas (SCC) arising from the Waldeyer ring and associated with human papillomavirus (HPV).
Cystic lymph nodes can be seen in as many as 50% of squamous cell carcinomas arising from the Waldeyer ring, and about 50% of all tonsil/base of tongue squamous cell carcinomas are positive for human papillomavirus. These cystic nodal metastases are typically located in the jugulodigastric region and can be moderately large and associated with relatively small or occult primary tumors.
The cyst formation in these lymph nodes is thought to be due to spontaneous degradation of keratin and cellular debris inside the lymph node or formation of a true epithelium-lined cyst in the center of the lymph node. It is not thought to be due to central necrosis as can be seen in cystic nodal metastases elsewhere.
Other head and neck cancers, notably papillary thyroid carcinoma, can result in cystic lymph node metastasis. Carcinoma arising in a branchial cleft cyst is now considered to be exceedingly rare. Indeed, many lesions previously diagnosed as branchial cleft carcinomas are now thought to have represented cystic metastasis from a tonsillar primary squamous cell carcinoma.