Inverted papilloma of the urinary bladder.

BACKGROUND

Inverted papillomas are rare in the lower urinary tract. It is a histologically benign tumor with low grade malignant potential. Association with transitional cell carcinoma has also been reported.

METHODS

Eight cases of inverted papilloma of the urinary bladder were diagnosed at this hospital between November 1990 and May 1994. There were one female and seven males with an average age of 63.5 years. We analyze their clinical presentations, histological findings and the outcome of treatments.

RESULTS

Four patients presented with hematuria, and four with obstructive symptoms. Four were solid pedunculated tumors; three were papillary pedunculated; and one was a papillary sessile tumor. All tumors were solitary with four located in the bladder neck, two in the lateral wall, one in the interureteral ridge, and one in the trigonal area. A 77-year-old man whose tumor coexisted with an infiltrative transitional cell carcinoma was treated with partial cystectomy. The other seven patients were treated by transurethral resection. All the tumors were of the trabecular type and three of them (37.5%) harbored calcium oxalate crystals. There was no evidence of recurrence in a median follow-up of 18 months.

CONCLUSIONS

Inverted papillomas of urinary bladder are benign tumors, which can be treated successfully by transurethral resection and fulguration of tumor bed. However, precautionary studies are necessary to exclude the coexistence of malignancy and annual follow-up with cystourethroscopy is mandatory.