What is the most likely diagnosis for a patient with a bloody nasal discharge and a biopsy showing neoplastic cells positive for keratin and Epstein-Barr nuclear antigen?

• A. Burkitt lymphoma
• B. Kaposi sarcoma
• C. Nasopharyngeal carcinoma
• D. Sinonasal carcinoma

Answer: (C)

The most likely diagnosis for a patient presenting with a bloody nasal discharge and a biopsy indicating neoplastic cells that are positive for keratin and Epstein-Barr nuclear antigen is nasopharyngeal carcinoma.

This type of cancer is strongly associated with Epstein-Barr virus (EBV), which is evidenced by the detection of EBV nuclear antigen in the neoplastic cells. Nasopharyngeal carcinoma typically arises in the nasopharynx and can present with symptoms such as bloody nasal discharge, nasal obstruction, and lymphadenopathy. The presence of keratin positivity indicates an epithelial origin, aligning with the characteristics of nasopharyngeal carcinoma, which commonly arises from squamous epithelial cells.

While Burkitt lymphoma and Kaposi sarcoma are also associated with EBV, they present differently: Burkitt lymphoma is a highly aggressive B-cell lymphoma and typically does not present with keratin positivity or bloody nasal discharge, while Kaposi sarcoma usually occurs as purplish lesions on the skin and is associated with HHV-8 rather than EBV. Sinonasal carcinoma is a broader diagnosis and can encompass several types, but the specificity of keratin and EBV positivity strongly points towards nasopharyngeal carcinoma.