Discerning primary tumors from metastases in synchronous nasopharyngeal squamous cell carcinoma and cutaneous squamous cell carcinoma: A case report and review of the literature.

Nasopharyngeal carcinoma is one of the most common types of malignant tumor in Southern China and Southeast Asia, and its etiology is closely associated with Epstein-Barr virus (EBV) infection. Non-keratinizing carcinoma accounts for >95% of all nasopharyngeal carcinoma cases. In addition, metastatic nasopharyngeal carcinoma from other locations in the body is extremely rare. This study reports the case of a 53-year-old female who presented with a lesion on the left nasal alar skin that had slowly developed over a five-year period. A biopsy was obtained and the lesion was histologically diagnosed as cutaneous squamous cell carcinoma (SCC). A nasopharyngeal neoplasm was also detected by 18-fluorine-2-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography and nasopharyngoscopy. A biopsy of the nasopharyngeal neoplasm confirmed a diagnosis of SCC. However, a small EBV-encoded nuclear RNA (EBER) test demonstrated that the nasopharyngeal tumor cells were all negative for EBV. As the majority of nasopharyngeal carcinomas were positive for EBER, it was concluded that the nasopharyngeal carcinoma had metastasized from the cutaneous SCC. A brief review of literature is also presented, in addition to a discussion of the pathogen, epidemiology and diagnosis of cutaneous and nasopharyngeal carcinomas.