Natural history of urothelial inverted papilloma

BACKGROUND. Inverted urothelial papilloma is an uncommon urothelial neoplasm. Although it is traditionally regarded as a benign tumor, conflicting data on multiplicity, recurrence rate, and association with urothelial carcinoma have left uncertainties concerning its biologic behavior. METHODS. The authors analyzed the clinicopathological characteristics of 75 cases of inverted papilloma in the urinary tract without prior or concurrent urothelial carcinoma to determine its biologic behavior and prognosis, and to correlate these findings with surveillance strategies. RESULTS. These patients ranged in age from 26 to 85 years (mean, 60 years). Of the 46 patients for whom tobacco use history was available, 28 gave a history of smoking. Inverted papillomas were located in the urinary bladder (67 cases), prostatic urethra (4 cases), and ureter (4 cases). The majority of vesical tumors arose from the trigone or near the bladder neck. Common presenting complaints included hematuria, dysuria, and irritative voiding symptoms. In 1 case of vesical inverted papilloma, there was a recurrence. All other patients were free of tumor recurrence or progression during a mean follow-up of 68 months (range, 2-240 months). CONCLUSIONS. Both the extremely low incidence of tumor recurrence (1%) and strikingly favorable prognosis suggest that inverted urothelial papilloma, when diagnosed according to strictly defined criteria, is a benign urothelial neoplasm not related to urothelial carcinoma. Therefore, complete transurethral resection of inverted papilloma is adequate surgical therapy, and surveillance protocols as rigorous as those employed in the management of urothelial carcinoma seem unnecessary.