Unusual presentation of HPV-positive squamous cell carcinoma of the nasolacrimal duct as carcinoma of unknown primary.

Most human papillomavirus (HPV)-positive carcinomas of unknown primary (CUP) in the cervical lymph nodes are ultimately found to arise from the oropharynx, which has by far the highest prevalence of HPV-positivity among head and neck tumors. However, HPV is also detected in a subset of tumors from other sites. In this case report, we describe the first reported instance of a lacrimal sac carcinoma presenting as an HPV-positive CUP. A 64-year-old male presented with isolated right-sided neck swelling, found on core biopsy to be HPV-positive squamous cell carcinoma (SCC). Initial diagnostic workup did not reveal a primary site, and he was treated for T0N1M0 oropharyngeal SCC with chemoradiation. Shortly afterwards he developed epiphora and was found to have an FDG-avid lesion along his inferior right orbit. Biopsy revealed HPV-positive SCC, presumed to be the true primary site of his previously diagnosed CUP. He was treated with surgical resection, proton-beam radiation, and carboplatin-paclitaxel. He had an excellent outcome with no evidence of disease 18 months following treatment completion. This case underscores the importance of continued vigilance and thorough investigation for a primary tumor site even when cervical nodal metastases are HPV-positive. While the vast majority of HPV-positive head and neck tumors arise in the oropharynx, other anatomical sites may also harbor HPV-positive malignancies.