What is the best management approach for inverted papilloma?

Management of Inverted Papilloma

The optimal management approach for inverted papilloma is complete surgical excision, with the specific surgical technique determined by the extent and location of the disease. 1

Classification and Diagnosis

Inverted papilloma is characterized by an endophytic growth pattern of urothelial tissue. According to the WHO/ISUP classification system, inverted papillomas can be categorized as:

• Inverted papilloma: Shows endophytic growth of non-hyperplastic, non-atypical urothelium with peripheral palisading and bland, spindled appearance 1
• Inverted PUNLMP (Papillary Urothelial Neoplasm of Low Malignant Potential): Hyperplastic urothelium growing in an endophytic pattern 1
• Inverted papillary urothelial carcinoma, low-grade: Shows greater cellularity, loss of polarity, and mild to moderate cytologic atypia 1
• Inverted papillary urothelial carcinoma, high-grade: Demonstrates greater loss of order, increased nuclear atypia, and potential for invasion 1

Surgical Management

Sinonasal Inverted Papilloma

For sinonasal inverted papillomas, the surgical approach depends on tumor location and extent:

1. Endoscopic approach:

   • First-line treatment for accessible lesions (nasal septum, lateral nasal wall)
   • Associated with lower recurrence rates (6-14%) compared to limited resections 2, 3
   • Advantages include fewer complications and improved access to specific nasal areas 4

2. Combined endoscopic and external approach:

   • Reserved for extensive disease, especially with significant maxillary sinus involvement
   • May be necessary when complete endoscopic visualization is not possible 5

3. Type-specific approaches (based on origin of lesion):

   • Type I (nasal septum and lateral nasal wall): Conservative transnasal endoscopic excision
   • Type II (maxillary sinus origin): Radical transnasal endoscopic medial maxillectomy 6

Urological Inverted Papilloma

For urological inverted papillomas:

• Complete transurethral resection with adequate sampling for histopathological evaluation
• Follow-up cystoscopy to monitor for recurrence

Follow-up Protocol

Long-term follow-up is essential due to:

1. Risk of recurrence: Recurrence rates vary by approach:

   • Endoscopic procedures: 12.8%
   • Lateral rhinotomy with medial maxillectomy: 17.0%
   • Limited resections: 34.2% 3

2. Risk of malignant transformation:

   • Synchronous carcinoma: 7.1% of cases
   • Metachronous carcinoma: 3.6% of cases
   • Mean time to develop metachronous carcinoma: 52 months (range 6-180 months) 3

Important Considerations

• Complete removal is critical: The primary goal is complete removal of all diseased mucosa to minimize recurrence risk 4
• Surgical expertise matters: Outcomes are better with surgeons experienced in managing inverted papillomas 5
• Histopathological evaluation: Proper evaluation is essential to document the benign nature and exclude invasive components 1
• Long-term surveillance: Extended follow-up (minimum 5 years) is recommended to detect late recurrences or malignant transformation 3

Pitfalls to Avoid

1. Inadequate initial resection: Incomplete removal significantly increases recurrence risk
2. Misdiagnosis: Inverted papillomas can be mistaken for inflammatory polyps; ensure proper histopathological examination
3. Insufficient follow-up: Recurrence and malignant transformation can occur years after initial treatment
4. Overlooking malignant components: Thorough sampling is necessary to detect areas of carcinoma within the papilloma

The ICUD recommends standardized terminology and criteria for inverted lesions to enable better understanding and management of these neoplasms going forward 1.