## Distinguishing NPC from OPSCC ### EBV Association — The Key Discriminator **Key Point:** EBV seropositivity is the most specific and discriminating feature of nasopharyngeal carcinoma. Elevated EBV IgA and IgG antibodies are found in >90% of undifferentiated NPC cases, making this a hallmark distinction. **High-Yield:** In endemic regions (Southeast Asia, North Africa, Southern China), EBV is detected in nearly all NPC cases. In contrast, OPSCC is predominantly HPV-driven (in developed countries) or tobacco/alcohol-related, with minimal EBV involvement. ### Comparison Table: NPC vs OPSCC | Feature | Nasopharyngeal Carcinoma | Oropharyngeal SCC | | --- | --- | --- | | **EBV association** | >90% (undifferentiated) | <5% | | **HPV association** | 5–10% | 60–80% (developed countries) | | **Tobacco/alcohol** | Minor role | Major risk factors | | **Cervical nodes** | Common (80%) | Common (60–70%) | | **Histology** | Undifferentiated, keratinizing, non-keratinizing | Well/moderately differentiated SCC | | **Geographic prevalence** | Southeast Asia, North Africa | Worldwide | ### Clinical Pearl **EBV serology in NPC:** - Elevated **anti-EBV IgA** (most specific) - Elevated **anti-EBV IgG** - These are used for screening and surveillance in endemic regions **Why other options are NOT discriminators:** - Cervical lymphadenopathy occurs in both NPC and OPSCC - Squamous cell histology is common to both - Tobacco/alcohol are risk factors for OPSCC but not NPC (though not exclusive) **Tip:** When comparing two head and neck malignancies on NEET PG, always ask: "What is the *unique* etiologic or molecular signature?" For NPC, that is **EBV**. 
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