A 42-year-old woman from Mumbai presents with a 6-month history of progressive unilateral left nasal obstruction and epistaxis. She reports no asthma, allergies, or systemic symptoms. On nasal endoscopy, a single, firm, vascular, pedunculated mass is seen arising from the lateral nasal wall near the sphenoid ostium, with a grayish-white surface and areas of bleeding. CT paranasal sinuses shows a heterogeneous mass with mixed density in the left nasal cavity and extending into the maxillary sinus. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Inverted Papilloma (Inverted Sinonasal Papilloma) ### Key Features in This Case **Key Point:** A unilateral, firm, vascular, pedunculated mass with epistaxis, mixed density on CT, and unilateral presentation in a middle-aged patient is highly suggestive of inverted papilloma (IP), a benign but locally aggressive tumor with malignant potential. ### Distinguishing Features of Inverted Papilloma | Feature | Inverted Papilloma | Antrochoanal Polyp | Hemangioma | CRSwNP | |---------|-------------------|-------------------|-----------|--------| | **Laterality** | Unilateral (90%) | Unilateral | Unilateral | Bilateral | | **Consistency** | Firm, vascular | Soft, gelatinous | Soft, compressible | Soft, pale | | **Bleeding** | Frequent epistaxis | Rare | Possible | Rare | | **Age** | 40–70 years | 10–30 years | Any age | 30–50 years | | **CT appearance** | Mixed density, heterogeneous | Homogeneous, smooth | Hyperdense, enhancing | Homogeneous, opacified sinuses | | **Origin** | Lateral nasal wall, ethmoid | Maxillary sinus ostium | Vascular tissue | Ostiomeatal complex | | **Malignant potential** | 5–15% → SCC | None | None | <1% | ### Pathological Features **High-Yield:** Inverted papilloma is characterized histologically by intact epithelial basement membrane with intact overlying mucosa, intact squamous epithelium inverting into underlying stroma (hence "inverted"), and intact basement membrane at the deep margin. This distinguishes it from exophytic papillomas. ### Clinical Presentation 1. **Unilateral nasal obstruction** (most common) 2. **Epistaxis** (due to friable, vascular surface) 3. **Rhinorrhoea and post-nasal drip** 4. **Otalgia or ear fullness** (if extending to nasopharynx) 5. **Absence of systemic symptoms** (unlike malignancy) **Clinical Pearl:** Epistaxis with a unilateral nasal mass is a red flag for inverted papilloma and should prompt urgent imaging and biopsy. ### Diagnostic Workup ```mermaid flowchart TD A[Unilateral nasal mass + epistaxis]:::outcome --> B[Nasal endoscopy]:::action B --> C{Appearance?}:::decision C -->|Firm, vascular, unilateral| D[Suspect IP]:::urgent C -->|Soft, pale, bilateral| E[Suspect CRSwNP]:::outcome D --> F[CT + MRI]:::action F --> G[Biopsy for histology]:::action G --> H{Confirmed IP?}:::decision H -->|Yes| I[FESS + wide local excision]:::action I --> J[Long-term endoscopic surveillance]:::action H -->|No| K[Manage accordingly]:::outcome ``` ### Imaging Characteristics **Key Point:** On CT, inverted papilloma shows: - **Mixed density** (soft tissue + hyperostotic bone) - **Cerebriform or columnar appearance** (columns of tumor separated by septa) - **Bone remodeling or erosion** (aggressive local behavior) - **Unilateral involvement** (90% of cases) MRI is superior for assessing dural involvement and distinguishing from malignancy (T2 hyperintense, T1 isointense). ### Management 1. **Surgical excision** via FESS with wide local excision and removal of involved periosteum 2. **Adjuvant radiation** if: - Dural involvement - Orbital involvement - Incomplete excision - Recurrence 3. **Endoscopic surveillance** every 3–6 months for first 2 years, then annually **Warning:** Recurrence rates are 10–30% even with complete excision. Malignant transformation to squamous cell carcinoma occurs in 5–15% of cases. [cite:Krouse 2000 Otolaryngology; Lawson et al. 2013 Head Neck Pathology] ### Why This Patient Has Inverted Papilloma The **unilateral** presentation, **firm and vascular** appearance, **epistaxis**, and **mixed-density CT appearance** with involvement of the maxillary sinus and sphenoid ostium are classic for inverted papilloma. The absence of bilateral, pale, soft polyps rules out CRSwNP.