Urothelial Papilloma Research Articles

Analysis of differentiation-associated proteins in rat bladder carcinogenesis.

Uroplakins are the major integral membrane proteins synthesized in terminally differentiated, superficial urothelial cells. Alteration of cell differentiation during rat urinary bladder carcinogenesis was analyzed immunohistochemically for the expression of uroplakins. Expression of uroplakins was compared in N-[4-(5-nitro-2-furyl)-2-thiazolyl]-formamide (FANFT)-, uracil-, sodium saccharin- or sodium ascorbate-induced urothelial simple hyperplasia, papillary-nodular hyperplasia, papilloma and carcinoma. In controls, uroplakins were located only in superficial cells, especially the luminal surface membrane. In FANFT-induced hyperplasia, including simple hyperplasia, intermediate cells also stained and the staining pattern was disorderly and intermittent. In uracil-induced simple hyperplasia, intermediate cells were stained but in an orderly fashion. In sodium saccharin- or sodium ascorbate-induced simple hyperplasia, superficial cells were swollen but alterations were not observed in the staining pattern. In carcinoma induced by FANFT and uracil, uroplakin expression was very disorderly and focal, usually with no expression on surface cells. It appears that disorderly differentiation is an index of bladder malignancy and is an early event in FANFT-induced lesions but a late event in uracil-, sodium saccharin- and sodium ascorbate-induced lesions.

Nuclear Deoxyribonucleic Acid Content in Inverted Papilloma of the Urothelium

We analyzed formalin-fixed and paraffin-embedded materials from urothelial inverted papillomas using flow-cytometric DNA analysis to investigate the intrinsic nature in terms of the malignant potentials. DNA indices of the inverted papillomas ranged between 1.00 and 1.26 with a mean value of 1.12. The percentage of S phase of a tumor DNA histogram showed greater values in every case compared with a normal DNA histogram. This tumor form could be thus regarded as a diploid neoplastic disease with a relatively higher proliferative activity, although 1 case showed an aneuploid pattern (DNA index = 1.26), in which bladder carcinoma developed subsequently.

Inverted papilloma of bladder: Clinical significance

Based on 15 cases of inverted urothelial papilloma, we present the clinical significance of these lesions in view of the current literature. An inverted papilloma should raise suspicion with respect to the whole urothelial surface. However, approaching every lesion of this type as a (pre-)neoplastic tumor does not seem justified, since 90 percent of all cases reported so far do not present any clinical or histologic feature of malignancy. Some factors, such as the patient's history, eventually associated urothelial carcinomas, or histologic features of malignant transformation within an inverted papilloma, must be taken into consideration. If no single indication in favor of malignancy has been disclosed, we believe follow-up with yearly endoscopic investigations, in addition to regular urine cytologies, may suffice.

Inverted papilloma of upper urinary tract

Two new cases of inverted urothelial papilloma in the upper urinary tract are described and added to the 22 cases previously reported in the literature. In both cases inverted papilloma was localized beneath macroscopic normal surface, and in one of the cases the changes were found scattered widely in the upper urinary tract. The possible etiology and the symptomatology are discussed, and the need for follow-up of these patients is emphasized.

Histology and histogenesis of two different types of inverted urothelial papillomas.

Inverted papillomas are rare tumors of the lower urinary tract. Among 1829 reclassified tumors of the urinary bladder, renal pelves, ureters, and urethra, there were 40 (2.2%) inverted papillomas. The great majority of these were localized in the bladder. Because of distinctive histologic features and patterns of growth it is possible to differentiate between two basic types of inverted papillomas which were termed "trabecular" and "glandular." The trabecular type consists of widely branched, anastomosing cords of urothelial cells originating directly from the overlying transitional epithelium. The trabeculae are arranged horizontally or perpendicularly to the surface epithelium and occasionally exhibit peripheral palisading of the cells. The glandular type is characterized by multiple round to oval islands of proliferated urothelial cells together with pseudoglandular and true glandular structures which are often still connected with the surface urothelium. The gland-like structures are lined by stratified urothelium, the true glands by mucus secreting columnar epithelium. Sometimes glandular metaplasia of an intestinal type with goblet cell formation could be observed. Inverted papillomas of the trabecular type arise histogenetically from a proliferation of the basal cells of the urothelium. The glandular type develops apparently from a proliferative cystitis cystica and glandularis which, therefore, should be considered a potentially preneoplastic lesion. The predominant view of the biological behavior of inverted papillomas is that of a benign neoplastic lesion. Morphologic findings supplied some arguments in favor of a low grade malignant potential of these tumors. However, their malignant transformation seemed to be much lower than that of exophytic papillomas.

Inverted papilloma and papillary transitional cell carcinoma of urinary bladder.Report of four cases of inverted papilloma, one showing papillary malignant transformation and review of the literature

Four new cases of inverted urothelial papillomas are described and added to the 47 cases previously reported in the literature. Three papillomas present benign gross and microscopic characteristics. The fourth case, however, demonstrates inverted papilloma and papillary transitional cell carcinoma in a single polypoid lesion. This papillary malignant transformation, not previously observed in inverted papillomas, cautions against overconfidence in benign nature of inverted papilloma.

Inverted Urothelial Papilloma

Summary Two examples of inverted urothelial papilloma are reported. One was from the renal pelvis, a site of origin not previously described. A study of serial sections showed that these lesions are not neoplasms, but an exaggerated form of the common urothelial crypt lesion.

Ureteral Tumors

<h3>To the Editor:—</h3> Certainly we can offer no solution to the problem of classifying urothelial papillomas. One cannot predict in which individuals other urothelial tumors will develop. In the case mentioned by Dr. Bergman, could not the vesical lesion which occurred five years after removal of a noninvasive ureteral papilloma have been a subsequent primary lesion? Concerning the urographic findings in ureteral tumors, we wish to emphasize that the pyelographic findings are often not specific. To make a preoperative diagnosis of ureteral tumors one should have a high index of suspicion and should invariably outline the entire ureter at the time of retrograde urography. The variety of urographic findings pointed out by Dr. Bergman would appear to add support to this proposition. Certainly the prognosis in ureteral tumors is guarded; however, this should not necessarily justify nephroureterectomy on an empiric basis in every case. In our group of patients with