## Histopathological Classification of Nasal Polyps **Key Point:** Inflammatory fibroid polyps (also called eosinophilic polyps or allergic polyps) are the most common benign nasal polyps, accounting for 90% of all nasal polyps. ### Histology of Inflammatory Fibroid Polyps - Composed of edematous stroma with abundant eosinophils, plasma cells, and lymphocytes - Loose fibrous tissue with minimal epithelial involvement - No malignant potential - Often associated with chronic rhinosinusitis and allergic rhinitis ### Other Nasal Polyp Types | Polyp Type | Frequency | Key Features | Malignant Potential | |---|---|---|---| | Inflammatory fibroid | 90% | Eosinophil-rich, edematous stroma | None | | Antrochoanal | 4–6% | Arises from maxillary sinus, extends into nasopharynx | None | | Inverted papilloma | 1–2% | Intact epithelium inverts into underlying stroma | High (5–15%) | | Allergic fungal sinusitis | Rare | Fungal hyphae in polyp, eosinophilic mucin | None | **High-Yield:** The term "allergic polyp" is often used interchangeably with inflammatory fibroid polyp because of the prominent eosinophilic infiltration, though not all cases have a documented IgE-mediated mechanism. **Clinical Pearl:** Inflammatory fibroid polyps are typically bilateral and multiple, whereas antrochoanal polyps are usually unilateral and solitary. [cite:Dhingra ENT 8e Ch 8] 
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