[Clinical studies of inverted papilloma of the bladder]

Clinical studies were conducted on 9 cases of inverted papilloma of the urinary bladder which were transurethrally resected between August, 1987 and July, 1995 at our hospital, in males between 29 and 81 years of age (mean:58.3). Six of the 9 inverted papillomas were localized at the bladder neck and 3 in the trigone. Cystoscopic examinations revealed that inverted papillomas were divided into two types, one with a thick and short stalk with a smooth surface and the other with a thin and long stalk with/without a partial papillary surface. The majority of the former was located in the trigone and all of the latter cases in the bladder neck, suggesting that the two types occurred at different sites. Pathological examination by Hematoxylin-Eosin staining demonstrated that 5 of the 9 cases were of the trabecular type and 4 were of the grandlar type. Immunohistochemically, none of the tumors were stained with the antiprostatic-specific-antigen antibody revealed. Follow-up periods after the operation were from 12 to 48 months(mean:26.6 months) and no recurrence was observed.