## Chromosomal Abnormalities in Nasopharyngeal Angiofibroma **Key Point:** Nasopharyngeal angiofibroma (NAF) is a benign but locally aggressive tumour with **no consistent or recurrent chromosomal abnormality** identified to date. This distinguishes it from many other head and neck tumours. ### Cytogenetic Profile Unlike other soft tissue tumours: - **Ewing sarcoma** has t(11;22) or t(12;22) with EWS-CHOP/EWS-FLI1 fusion - **Synovial sarcoma** has t(X;18) with SS18-SSX fusion - **NAF remains cytogenetically heterogeneous** — no pathognomonic translocation **High-Yield:** The absence of a specific chromosomal marker makes NAF diagnosis **purely histopathological** — based on microscopic appearance (prominent vasculature, fibroblastic stroma, absence of atypia) rather than molecular testing. ### Clinical Significance - Diagnosis is **clinical + imaging + histology**, not molecular - The benign nature is confirmed by lack of malignant transformation markers - Recurrence is due to **incomplete surgical removal**, not genetic progression **Clinical Pearl:** NAF occurs almost exclusively in adolescent males (peak 15–25 years), suggesting a **hormonal rather than genetic driver** — likely androgen-dependent growth. [cite:Harrison 21e Ch 197]
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