Evaluation of urinary inverted papillomas: a report of 13 cases and literature review

Inverted urothelial papilloma: A rare pathology in young girl. A case report and literature review

Bladder cancer is relatively common in the general population but is considered a rare entity in children. Rhabdomyosarcoma is the most frequently encountered bladder tumor in children. Inverted papilloma of the urinary bladder is a rare presentation in adults and is considered extremely rare in the pediatric age group. We report a case of inverted urothelial papilloma (IUP) in the bladder in an 8-year-old girl who presented with painless gross hematuria. Radiological investigations, cystoscopy, and histological examination revealed the rare pathology of IUP of the bladder and a resection was performed. No recurrence was encountered after 3 years of follow-up.

Inverted urothelial papilloma of the upper urinary tract: description of two cases with systematic literature review

BACKGROUND

Inverted urothelial papilloma (IUP) of the upper urinary tract is an uncommon benign tumour that occasionally presents as a polypoid mass causing urinary obstruction. Histologically, IUP is characterised by a proliferating urothelium arranged in cords and trabeculae, in continuity with overlying intact epithelium, and extending into the lamina propria in a non-invasive, endophytic manner. Cytological atypia is minimal or absent. Top differential diagnoses include urothelial carcinoma with inverted growth pattern and florid ureteritis cystica. Although urothelial carcinomas of the upper urinary tract with prominent inverted growth pattern commonly harbour microsatellite instability, the role of the mutator phenotype pathway in IUP development is still unclear. The aim of this study was to describe two additional cases of IUP of the upper urinary tract, along with an extensive literature review.

CASE PRESENTATION

We observed two polypoid tumours originating in the renal pelvis and the distal ureter, respectively. Both patients, a 76-year-old woman and a 56-year-old man, underwent surgery because of the increased likelihood of malignancy. Histology was consistent with IUP and patients are alive and asymptomatic after long-term follow-up (6 years for the renal pelvis lesion and 5 years for the ureter lesion). The tumours retained the expression of the mismatch-repair protein MLH1, MSH2, and PMS2 whereas loss of MSH6 was found in both cases.

CONCLUSIONS

When completely resected, IUP does not require rigorous surveillance protocols, such as those for urothelial carcinoma and exophytic urothelial papilloma. It is therefore important for the surgical pathologist to be aware of this rare entity in order to ensure correct patient management.

Overactivity or blockade of transforming growth factor-β each generate a specific ureter malformation

Transforming growth factor-β (TGFβ) has been reported to be dysregulated in malformed ureters. There exists, however, little information on whether altered TGFβ levels actually perturb ureter development. We therefore hypothesised that TGFβ has functional effects on ureter morphogenesis. Tgfb1, Tgfb2 and Tgfb3 transcripts coding for TGFβ ligands, as well as Tgfbr1 and Tgfbr2 coding for TGFβ receptors, were detected by quantitative polymerase chain reaction in embryonic mouse ureters collected over a wide range of stages. As assessed by in situ hybridisation and immunohistochemistry, the two receptors were detected in embryonic urothelia. Next, TGFβ1 was added to serum-free cultures of embryonic day 15 mouse ureters. These organs contain immature smooth muscle and urothelial layers and their in vivo potential to grow and acquire peristaltic function can be replicated in serum-free organ culture. Such organs therefore constitute a suitable developmental stage with which to define roles of factors that affect ureter growth and functional differentiation. Exogenous TGFβ1 inhibited growth of the ureter tube and generated cocoon-like dysmorphogenesis. RNA sequencing suggested that altered levels of transcripts encoding certain fibroblast growth factors (FGFs) followed exposure to TGFβ. In serum-free organ culture exogenous FGF10 but not FGF18 abrogated certain dysmorphic effects mediated by exogenous TGFβ1. To assess whether an endogenous TGFβ axis functions in developing ureters, embryonic day 15 explants were exposed to TGFβ receptor chemical blockade; growth of the ureter was enhanced, and aberrant bud-like structures arose from the urothelial tube. The muscle layer was attenuated around these buds, and peristalsis was compromised. To determine whether TGFβ effects were limited to one stage, explants of mouse embryonic day 13 ureters, more primitive organs, were exposed to exogenous TGFβ1, again generating cocoon-like structures, and to TGFβ receptor blockade, again generating ectopic buds. As for the mouse studies, immunostaining of normal embryonic human ureters detected TGFβRI and TGFβRII in urothelia. Collectively, these observations reveal unsuspected regulatory roles for endogenous TGFβ in embryonic ureters, fine-tuning morphogenesis and functional differentiation. Our results also support the hypothesis that the TGFβ up-regulation reported in ureter malformations impacts on pathobiology. Further experiments are needed to unravel the intracellular signalling mechanisms involved in these dysmorphic responses. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

The pathology of urinary bladder lesions with an inverted growth pattern

Inverted lesions in the urinary bladder have been the source of some difficulty in urological pathology. The two common ones are von Brunn's nests and cystitis cystic/cystitis glandularis, which are considered normal variants of urothelium. Apart from them, a number of other rare urothelial lesions with inverted growth pattern occur in the urinary bladder. Some of them are only reactive conditions, just as pseudocarcinomatous hyperplasia. Some are benign tumors, namely inverted papilloma. Whereas others are malignant neoplasms, including inverted papillary urothelial neoplasm of low malignant potential (PUNLMP), non-invasive inverted papillary urothelial carcinoma (low-grade and high-grade), and invasive urothelial carcinoma (inverted, nested and big nested variants). Because of the overlapping morphological features of all the inverted lesions mentioned above, even between high-grade invasive carcinoma and pseudocarcinomatous hyperplasia which are only a kind of reactive conditions, it is very important for the surgical pathologist to recognize and be familiar with these inverted lesions in urinary bladder. In this article, we review these spectrums of inverted lesions of the urinary bladder. Emphasis is placed on histogenesis, morphology, differential diagnosis of these lesions, and the pathologic grading of the non-invasive inverted neoplasms, such as inverted papilloma, inverted PUNLMP, non-invasive inverted papillary urothelial carcinoma with low-grade, and non-invasive inverted papillary urothelial carcinoma with high-grade.

A clinical and molecular review of inverted papilloma of the urinary tract: how to handle?

Inverted papilloma (IP) of the urinary tract is classified by the World Health Organisation as a non-invasive urothelial tumour with normal to minimal cytological atypia of the neoplastic cells. During the 1980s, it came under suspicion of having a premalignant or malignant potential and of being concurrent with urothelial cell carcinoma (UCC). This quandary has been proven difficult to solve, due to the fact that IP is very rare and literature mostly consists of case reports with varying levels of information, making strong meta-analyses problematic. New immunohistochemical techniques and genetic approaches are more frequently being used in the attempt to achieve better classifications, prognosis and treatment of lesions hereunder IP. This review will, in our awareness, be the first to combine the knowledge from retrospective studies with these new approaches for determining a possible premalignant potential and concurrency with UCC and subsequently outline a recommendation for follow-up.

Long-term clinical outcome of inverted urothelial papilloma including cases with focal papillary pattern: is continuous surveillance necessary?

OBJECTIVE

To investigate the necessity for continuous cystoscopic surveillance of inverted papilloma (IP), including tumors exhibiting mixed morphology (IP with focal papillary architecture).

METHODS

We retrieved all cases of de novo ("primary") IP, diagnosed in our institution during 10 years (from January 2000 to December 2009), from the information database. Patients with a history of urothelial carcinoma or concurrent urothelial carcinoma were excluded. Surveillance was performed by routine cystoscopy, and follow-up was obtained from our institutional and regional clinical and pathology databases.

RESULTS

We identified 35 patients with IP, including 3 with focal papillary architecture. Mean patient age was 60 years (range, 26-88) with male-to-female ratio of 1.9:1. Most common tumor location was urinary bladder (86%), followed by urethra (14%). Focal papillary architecture was identified in 3 patients (aged 51, 52, and 78 years). Mean follow-up was 66 months (median 68; range, 11-132). Only 1 male patient (age 81) had a subsequent diagnosis of IP on follow-up cystoscopy at 9 months; no recurrence or progression was documented in the other patients diagnosed with IP.

CONCLUSION

The absence of progression of IP on long-term follow-up in this study strongly argues against the need of continuous surveillance for patients in whom (1) strict diagnostic criteria are followed, (2) a complete resection can be ascertained, and (3) no previous or concurrent urothelial malignancies are documented. In this study, the 3 patients with IP showing focal papillary architecture had a benign course, similar to the previously documented cases.

Upper urinary tract inverted papillomas: Report of 10 cases

The aim of the study was to review the clinical features and treatments of 10 (9 males and 1 female; age range, 61-73 years; median age, 67 years) upper urinary tract inverted papilloma (IP) cases between 1995 and 2010. The clinical syndromes, diagnostic procedures, treatments and results of the follow-up were evaluated. The results showed that the site of tumor development was the ureter in 6 cases and the renal pelvis in 4 cases. It was also identified that 7 tumors developed on the left side and 3 developed on the right side of the ureter and renal pelvis, respectively. A nephroureterectomy was performed in the first 6 cases, while a partial ureterectomy was performed in 3 cases and a local resection was performed endoscopically in 1 case. All but 2 tumors were solitary, ranging from 5 to 30 mm in diameter. Occurrence in association with transitional cell carcinoma was identified in one case. All 10 patients were subject to follow-up (range, 19-120 months; median, 59 months), during which no recurrence was found. Local excision is considered as adequate treatment when upper urinary tract IP is diagnosed according to strictly defined criteria.

Inverted papilloma of the bladder: a review and an analysis of the recent literature of 365 patients

OBJECTIVES

Until the 1970s, inverted urothelial papilloma (IUP) of the bladder was generally regarded as a benign neoplasm. However, in the 1980s, several reported cases suggested the malignant potential of these papillomas, including cases with features indicative of malignancy, recurrent cases, and cases of IUP synchronous or metachronous with transitional cell carcinoma. The aim of this systematic review and analysis of the literature since 1990 to date is to contribute to unresolved issues regarding the biological behavior and prognosis of these neoplasms to establish some key points in the clinical and surgical management of IUP.

MATERIALS AND METHODS

Database searches yielded 109 references. Exclusion of irrelevant references left 10 references describing studies that fulfilled the predefined inclusion criteria.

RESULTS

One problem regarding these neoplasms is the difficulty of obtaining a correct histopathologic diagnosis. The main differential diagnosis is endophytic urothelial neoplasia, including papillary urothelial neoplasia of low malignant potential or urothelial carcinoma of low or high grade, while other considerably rare differential diagnoses include nephrogenic adenoma, paraganglioma, carcinoid tumor, cystitis cystica, cystitis glandularis, and Brunn's cell nests. The size of the lesions ranged from 1 to 50 mm (mean 12.8 mm). Most cases occurred in the fifth and sixth decade of life. The mean age of affected patients was 59.3 years (range 20-88 years). Analysis of the literature revealed a strong male predominance with a male/female ratio of 5.8:1. The most commonly reported sites of IUP were the bladder neck region and trigone. Of 285 cases included in 8 studies, 12 cases (4.2%) were multiple. Out of the total of 348 patients, 6 patients (1.72%) had a previous history of transitional cell carcinoma of the urinary bladder, 5 patients (1.43%) had synchronous transitional cell carcinoma of the urinary bladder, and 4 patients (1.15%) had subsequent transitional cell carcinoma of the urinary tract. The time before recurrence was <45 months (range 5-45 months, mean 27.7 months) after surgery.

CONCLUSIONS

Inverted papilloma could be considered a risk factor for transitional cell carcinoma, and it is clinically prudent to exclude transitional cell cancer when it is diagnosed. Follow-up is needed if the histologic diagnosis is definitive or doubtful. We recommend 4-monthly flexible cystoscopy for the first year and then every 6 months for the subsequent 3 years. Routine surveillance of the upper urinary tract in cases of inverted papilloma of the lower part of the urinary tract is not deemed necessary.