Inverted urinary papilloma: report of five cases and review of the literature.

Five new cases of inverted urinary papilloma are described and 13 previously reported cased are reviewed. All 18 examples were seen in adult males, with ages ranging from 26 to 79 years (average 57 years). Ten patients presented with symptoms of bladder outlet obstruction and 8 with haematuria. With one probable exception all of the tumours were solitary. Sixteen were found in the region of the bladder neck and prostatic urethra, and only 2 occurred on other sites. The papillomas were pedunculated or sessile and ranged in size from a few mms to 3 cms in greatest diameter. Most had smooth surfaces in contrast to the usual exophytic papillary urothelial neoplasms. Microscopically they showed a striking resemblance to the inverted papillomas of the nasal cavity and paranasal sinuses. In those examples where the stalk or base of the papilloma was included in the sections, there was no evidence of invasion of the underlying smooth muscle. Fourteen of the patients have been followed for periods ranging from 7 months to 11 years (average 2.5 years) and no recurrences have been documented. Simple local resection, by the transurethral route where possible, appears to be adequate treatment for these distinctive papillomas.