A 50-year-old Chinese man presents with a painless neck mass. Examination reveals a mass in the posterolateral neck. Nasopharyngoscopy shows a subtle submucosal bulge in the lateral wall of the nasopharynx (fossa of Rosenmüller). The most specific serological marker used in diagnosis and monitoring of this tumor is:

• A Serum IgA antibodies to EBV VCA (viral capsid antigen)
• B CEA (carcinoembryonic antigen)
• C Serum EBV plasma DNA (cell-free EBV DNA) ✓
• D Alpha-fetoprotein

Explanation

Nasopharyngeal carcinoma (NPC) is strongly associated with Epstein-Barr virus, particularly undifferentiated types (WHO type III), prevalent in Southeast Asian and Chinese populations. While IgA VCA antibodies are sensitive for screening, plasma EBV DNA (cell-free circulating EBV DNA) is the most specific and quantitative marker used for diagnosis, staging, treatment response monitoring, and detecting residual/recurrent disease after chemoradiotherapy. Levels correlate with tumor burden and normalize with complete response. CEA and AFP are not relevant to NPC.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.