Urothelial papilloma of the bladder. Clinical and biologic implications.

BACKGROUND: An international consensus has been reached regarding diagnostic criteria for papilloma of the urinary bladder. However, the incidences of recurrence and progression in patients with urothelial papilloma are uncertain.

METHODS: The population for this study consisted of 52 patients who were diagnosed with urothelial papilloma of the bladder at the Mayo Clinic between 1914 and 1998. All histologic slides were reviewed and fulfilled the diagnostic criteria of urothelial papilloma from the 1998 World Health Organization/International Society of Urological Pathology classification system. No patients had previous or coexistent urothelial carcinoma, and none were treated after biopsy.

RESULTS: The mean patient age at diagnosis was 57 years (range, 22-89 years). The male-to-female ratio was 1.9:1. The mean follow-up was 9.8 years (range, 0.1-58 years). Four patients developed recurrent papilloma (mean interval from diagnosis to recurrence, 3.3 years); 1 other patient developed papillary neoplasm of low malignant potential (Ta WHO Grade 1 papillary urothelial carcinoma) 6 years after the initial diagnosis of papilloma. None of these patients developed dysplasia, carcinoma in situ, or invasive urothelial carcinoma or died of bladder cancer.

CONCLUSIONS: Patients with urothelial papilloma have a low incidence of recurrence and rarely, if ever, develop urothelial carcinoma.