Which of the following is the most characteristic histopathological feature of nasopharyngeal angiofibroma?

Explanation

## Histopathology of Nasopharyngeal Angiofibroma **Key Point:** NAF is characterized by a **benign fibrovascular lesion** with abundant fibrous tissue interspersed with numerous large, dilated, thin-walled blood vessels that lack a muscular layer (deficient tunica media). ### Microscopic Features | Feature | Characteristic | |---------|----------------| | **Fibrous component** | Abundant, mature fibrous tissue | | **Vascular component** | Large, dilated, thin-walled vessels | | **Vessel wall** | Deficient or absent muscular layer (tunica media) | | **Endothelium** | Normal, intact | | **Mitotic activity** | Absent or minimal (benign) | | **Necrosis** | Absent | | **Epithelial covering** | Usually absent or denuded | ### Why This Matters Clinically **Clinical Pearl:** The **lack of muscular support in vessel walls** explains why NAF is so prone to hemorrhage and why epistaxis is the cardinal presenting symptom. The vessels cannot contract effectively to control bleeding. **High-Yield:** The combination of **abundant fibrous tissue + numerous large, thin-walled vessels** is pathognomonic for NAF and distinguishes it from other nasopharyngeal masses. ### Benign Nature - No mitotic figures or atypia - No necrosis - No invasion of surrounding tissues (though it may erode bone) - Never undergoes malignant transformation