## Diagnosis: Undifferentiated Carcinoma (WHO Type III) of the Nasopharynx ### Clinical Presentation The patient presents with classic features of nasopharyngeal carcinoma (NPC): - Unilateral nasal obstruction and epistaxis (early local symptoms) - Cervical lymphadenopathy (often the first sign in advanced disease) - Vascular mass on endoscopy (highly suggestive of NPC) ### Histopathology and WHO Classification | WHO Type | Histology | EBV Association | Geographic Pattern | Prognosis | |----------|-----------|-----------------|-------------------|----------| | Keratinizing SCC | Keratin pearls, well-differentiated | Weak | Western countries | Better | | Differentiated Non-keratinizing | Intact epithelium, minimal keratinization | Moderate | Intermediate | | **Undifferentiated (Type III)** | **Loss of differentiation, syncytial pattern** | **Strong (>95%)** | **Southeast Asia, Southern China** | **Worse** | **Key Point:** EBV-positive undifferentiated carcinoma (WHO Type III) is the most common histological type in endemic areas like South India and Southeast Asia. ### EBV Association **High-Yield:** Positive EBV in situ hybridization (EBER probe) in an undifferentiated carcinoma is pathognomonic for NPC Type III. This is one of the strongest viral-cancer associations in human oncology. ### Clinical Pearl The combination of: - Undifferentiated histology - EBV positivity - Southern Indian origin - Cervical lymphadenopathy as presenting feature ...makes WHO Type III undifferentiated carcinoma the diagnosis. ### Staging and Management Implications EBV-positive undifferentiated NPC typically presents at advanced stage (Stage III–IV) due to early cervical node involvement and occult distant metastases. Treatment is concurrent chemoradiotherapy (CCRT) ± induction/adjuvant chemotherapy [cite:NCCN Head & Neck Cancer Guidelines]. [cite:WHO Classification of Head and Neck Tumours 5e] 
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