Hidden Hypopharyngeal Primary of HPV Associated Lymphoepithelial-Like Carcinoma Presenting with Lymph Node Metastasis

Background: Lymphoepithelial-like carcinoma of the pharynx is a recently described sub-entity of HPV-associated pharyngeal squamous cell carcinoma. This histological entity might become an important differential diagnosis of cervical lymph node metastasis to its well known EBV-associated epipharyngeal counterpart.

Methods and results: We report on a patient presenting with a cervical cystic mass. Clinical findings and fine needle aspiration cytology was compatible with a second branchial arch cyst. Consecutive excision showed a lymph node with poorly differentiated lymphoepithelial-like squamous cell carcinoma, suggestive for a metastasis of an oropharyngeal primary. The patient underwent pandendoscopy with suspected primary in the epi- or oropharynx as suggested by the molecular characteristics of the tumor. The primary tumor was finally identified as a HPV 16 associated lymphoepitheliallike carcinoma in the tongue base and vallecula.

Conclusion: The final diagnosis of a HPV16-associated lymphoepithelial-like carcinoma has recently gained interest in the literature and the presented manifestation in the vallecula is an important differential diagnosis to EBV-associated epipharyngeal lymphoepithelial carcinoma.