[Inverted type urothelial cell bladder papillomas. Three new cases (author's transl)]

The authors report 3 new cases of inverted bladder papillomas, the first presenting with hematuria and the others at the time of urological examination for dysuria due to prostatic hypertrophy. Intravenous urography showed the tumour as a regular polycyclic filling defect of the base of the bladder. Macroscopically, such tumours are polypoid, whitish-grey and firm in consistency. Histologically, they are surrounded by a thin paramalpighian epithelium from which there is deep penetration of layers of tumour with an intact basal membrane and well differentiated paramalpighian type tumour cells without mitosis. The authors feel that this particular type of benign tumour develops from the sub-trigonal glands of Home, passing via the intermediate stage of the islets of von Brunn. The special histological characteristics of these inverted bladder papillomas suffice to distinguish them from other epithelial tumours with an uncertain prognosis.