Sinonasal Inverted Papilloma and Clinical Significance of Dysplasia: A Multi-Institutional Study.

OBJECTIVES

Sinonasal inverted papilloma (SNIP) is a benign sinonasal tumor with a tendency to recur and potential for malignant transformation. Dysplasia may be present, ranging from mild to severe. We aim to evaluate the effect of dysplasia on tumor behavior and patient outcomes.

METHODS

Retrospective chart review of SNIP cases from 2002 to 2023 treated by fellowship-trained Rhinologists at seven institutions. Clinical data were extracted, and tumors were histologically confirmed.

RESULTS

Four hundred and forty-eight patients were eligible for analysis. The mean age was 58 years with an average postoperative surveillance of 27 months. Most patients had tumors without dysplasia (74.3%), followed by severe (10.5%), mild (10.0%), and moderate (5.1%) dysplasia. The overall recurrence rate was 11.6%. Unifocal attachment was most prevalent in tumors without dysplasia. Among patients with multifocal attachment, recurrence was highest in those with severe dysplasia (38.1%) compared to no dysplasia (17.2%). Unifocal attachment was associated with improved recurrence-free survival in all three histology types (without, mild, and moderate dysplasia).

CONCLUSION

In the largest study to date examining the effect of dysplasia on patient outcomes, we found that SNIP that has severe dysplasia to be high risk for recurrence while the other three types of dysplasia to be of lower risk. We therefore propose a two-tiered grading system to improve consensus among pathologists and to guide patient counseling. In the treatment of SNIP, high-risk dysplasia is more often associated with multifocal attachment pattern and remains the most challenging to treat.