Inverted papilloma of the urinary bladder is a rare urothelial neoplasm, almost benign in its histologic morphology and clinical behavior. It occurs mainly in males and in the region of the trigone of bladder, or posterior urethra. But, it may
arise in
the renal pelvis. The characteristic downward proliferation of urothelial cells within the underlying lamina propria is of such magnitude as to an exophytic papillomatous tumor. The lesion may be easily mistaken for a lowgrade papillary
transitional
cell carcinoma, although the histologic appearance is distinctly different, as is its subsequent behavior. Behavior. Because of distinctive histologic features and patterns of growth it is possible to differentiate between two basic types of
inverted
papillomatous which were termed "trabecular" and "glandular".
The trabecular type consists of widely branchedd, anastomosing cords of urothelial cells criginating directly from the overlving transtional epithelium,. The glandular type develops apparently from a proliferative cystitis cystica and glandularis
which,
therefore, should be considered a popillomas of urinary tract and therefore they are no longer regarded as innocuous benign neoplasms. We report the 3 cases of inverted papilloma of the urinary bladder with a brief review of literature.
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