Clinical studies on inverted papilloma of the urinary tract: Report of 48 cases and review of the literature

Purpose: We report on 48 clinicopathologic cases of inverted papilloma and present the clinical significance attributed to these lesions in terms of the current literature. Materials and Methods: From 1976 to 2002 we had experience with 48 cases of inverted papilloma in urinary tract. We present the clinical features of these cases and report the results of prognosis research. Results: Patient age ranged from 24 to 82 years (mean 56). Coexistence of transitional cell carcinoma occurred in a different location in the bladder in 3 cases and within a single neoplasm in the ureter in 2. Followup data were available in 42 of the 48 cases. Followup ranged from 8 months to 23 years 6 months (mean 8 years 1 month). Of the 42 cases 3 (7%) had a recurrence and range from initial resection at 5 months, 1 year 4 months and 2 years 6 months, respectively. Conclusions: Our study suggests that there are 2 types of urinary inverted papilloma. The lesions in 1 type behave in a benign fashion and in another they have malignant potential. At this time we have no strategy with which to distinguish the 2 types of urinary inverted papilloma. Our results indicate that we must follow all cases for at least more than 2 years after initial treatment.