THE PROGNOSTIC VALUE OF A PRIMARY INVERTED PAPILLOMA OF THE URINARY TRACT

RAS Family Gene Mutations, Clinicopathological Features, and Spread Patterns of Inverted Urothelial Papilloma of the Bladder

Inverted urothelial papilloma (IUP) is a benign neoplasm characterized by a downgrowth of the urothelium beneath the surface of morphologically normal urothelial cells; however, the molecular features of IUP and their association with clinicopathological characteristics are unclear. In this study, we aimed to investigate the mutational landscape, clinicopathological features, genotype-phenotype associations, and spread patterns of IUP. We performed targeted next-generation sequencing of 39 consecutive IUP cases, the largest series investigated to date, and identified oncogenic driver mutations in RAS family genes in 34 cases (87%). HRAS mutations were the most prevalent (28 cases), which included Q61R (15 cases), followed by KRAS (5 cases) and NRAS (1 case) mutations. Characteristic mutations observed in urothelial carcinoma, including those in FGFR3 , TP53 , or the TERT promoter, were absent. HRAS -mutated IUPs were associated with a history of smoking ( P = 0.017) and streaming morphology ( P < 0.001), corresponding to the trabecular subtype. In contrast, all KRAS -mutated IUPs occurred in never-smoking patients ( P = 0.001) and showed cystic changes in morphology ( P = 0.005), corresponding to the glandular subtype. RAS Q61R immunohistochemistry visually revealed the neoplastic nature of the overlying cells and distinct spread patterns of IUP cells within the surface, including pseudoinfiltrative spread. No recurrence or carcinoma development was observed in any of the IUP cases during the follow-up period. Thus, we confirmed the importance of RAS pathway activation in IUP pathogenesis, an association between RAS family gene mutations and IUP subtypes, and the spread patterns of IUP cells within the surface.

Proteomic-Based Machine Learning Analysis Reveals PYGB as a Novel Immunohistochemical Biomarker to Distinguish Inverted Urothelial Papilloma From Low-Grade Papillary Urothelial Carcinoma With Inverted Growth

Background

The molecular biology of inverted urothelial papilloma (IUP) as a precursor disease of urothelial carcinoma is poorly understood. Furthermore, the overlapping histology between IUP and papillary urothelial carcinoma (PUC) with inverted growth is a diagnostic pitfall leading to frequent misdiagnoses.

Methods

To identify the oncologic significance of IUP and discover a novel biomarker for its diagnosis, we employed mass spectrometry-based proteomic analysis of IUP, PUC, and normal urothelium (NU). Machine learning analysis shortlisted candidate proteins, while subsequent immunohistochemical validation was performed in an independent sample cohort.

Results

From the overall proteomic landscape, we found divergent ‘NU-like’ (low-risk) and ‘PUC-like’ (high-risk) signatures in IUP. The latter were characterized by altered metabolism, biosynthesis, and cell–cell interaction functions, indicating oncologic significance. Further machine learning-based analysis revealed SERPINH1, PKP2, and PYGB as potential diagnostic biomarkers discriminating IUP from PUC. The immunohistochemical validation confirmed PYGB as a specific biomarker to distinguish between IUP and PUC with inverted growth.

Conclusion

In conclusion, we suggest PYGB as a promising immunohistochemical marker for IUP diagnosis in routine practice.

Case of inverted papillary urothelial carcinoma in the ureter

Introduction

Urothelial neoplasms with a varus growth pattern are rare, and few urologists have encountered inverted urothelial carcinoma of the ureter.

Case presentation

An 82‐year‐old man was referred to our hospital for investigation of gross hematuria. Magnetic resonance imaging revealed nodules measuring 1–2 mm in diameter in the left upper ureter with slight reduction in signal intensity on diffusion‐weighted imaging. Ureteroscopy showed a pedunculated smooth tumor that had the appearance of an inverted papilloma rather than the papillary shape typical of urothelial carcinoma. The tumor was biopsied and histopathological examination revealed a noninvasive, low‐grade urothelial carcinoma with inverted multiple layers. Laparoscopic radical nephroureterectomy was subsequently performed, and a pedunculated tumor measuring 20 mm in diameter was found in the left upper ureter. The histopathological diagnosis was inverted papillary urothelial carcinoma, low‐grade, pTa, pN0.

Conclusion

This report provides the first clinical description of inverted papillary urothelial carcinoma of the ureter.

Sinonasal inverted papilloma associated with small cell neuroendocrine carcinoma: A case report and literature review of rare malignancies associated with inverted papilloma

We report a rare case of sinonasal inverted papilloma (IP) associated with small cell neuroendocrine carcinoma (SNEC). To our knowledge, this is the first report to describe SNEC found during the treatment of sinonasal IP. Surgery and five cycles of cisplatin plus etoposide with concurrent intensity modulated radiation therapy were performed. Neither local recurrence nor distant metastasis was noted during 6 years of post-diagnostic follow-up. The prognosis of SNEC is very poor. Treatment planning for sinonasal IP should consider a possible association with this rare but aggressive malignancy, whose treatment is completely different from that of squamous cell carcinoma, a malignancy which is commonly associated with IP. We also performed a PubMed review of the literature to identify the incidence and pathological diagnosis of associated malignancy. Among a total of 5286 cases of sinonasal IP (61 studies), the incidence of associated malignancy was 8.02% in squamous cell carcinoma, 0.19% in transitional cell carcinoma, 0.04% in mucoepidermoid carcinoma, 0.02% in verrucous cell carcinoma and 0.02% in adenocarcinoma. The incidence of associated malignancy was significantly higher in East and Southeast Asia (11.0%) and North America (10.4%) than in Europe (3.9%) (p=0.04 and p=0.03, respectively; T-test).

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.

Immunohistochemistry and Fluorescence In Situ Hybridization Can Inform the Differential Diagnosis of Low-Grade Noninvasive Urothelial Carcinoma with an Inverted Growth Pattern and Inverted Urothelial Papilloma

Urothelial carcinoma (UC) comprises a heterogeneous group of epithelial neoplasms with diverse biological behaviors and variable clinical outcomes. Distinguishing UC histological subtypes has become increasingly important because prognoses and therapy can dramatically differ among subtypes. In clinical work, overlapping morphological findings between low-grade noninvasive UC (LGNUC), which exhibits an inverted growth pattern, and inverted urothelial papilloma (IUP) can make subclassification difficult. We propose a combination of immunohistochemistry (IHC) and molecular cytogenetics for subtyping these clinical entities. In our study, tissue microarray immunohistochemical profiles of Ki-67, p53, cytokeratin 20 (CK20) and cyclinD1 were assessed. Molecular genetic alterations such as the gain of chromosomes 3, 7 or 17 or the homozygous loss of 9p21 were also assessed for their usefulness in differentiating these conditions. Based on our analysis, Ki-67 and CK20 may be useful for the differential diagnosis of these two tumor types. Fluorescence in situ hybridization (FISH) can also provide important data in cases in which the malignant nature of an inverted urothelial neoplasm is unclear. LGNUC with an inverted growth pattern that is negative for both Ki-67 and CK20 can be positively detected using FISH.

MRI Findings of Inverted Urothelial Papilloma of the Bladder

OBJECTIVE

The objective of this study was to characterize MRI findings of inverted urothelial papilloma of the bladder.

MATERIALS AND METHODS

Data pertaining to 16 patients with 18 pathologically proven inverted urothelial papillomas of the bladder who had undergone MRI were retrospectively collected from seven institutions. The shape and surface characteristics of the tumors were evaluated using T2-weighted MR images. In addition, the signal intensity of inverted urothelial papillomas was visually assessed on T1-weighted, T2-weighted, and DW images and on early and delayed phase contrast-enhanced images.

RESULTS

The shape of the 18 inverted urothelial papillomas of the bladder was classified as polypoid with a stalk for 16 tumors (89%) and polypoid without a stalk for two tumors (11%). All stalks were surrounded by urine in the bladder. A total of 15 of the tumor surfaces (83%) were nonpapillary and three (17%) were papillary. All 12 of the inverted urothelial papillomas for which evaluable T1-weighted images were available were isointense with the bladder wall. The lesions had a slightly higher signal intensity than the bladder wall in 15 of the patients (83%) and showed isointensity with the bladder wall in three patients (17%). A total of three patients (17%) had tiny hyperintense foci noted on T2-weighted images. All 16 of the inverted urothelial papillomas examined by DWI had very high signal intensity. All 13 of the lesions for which early phase images were obtained using dynamic contrast-enhanced MRI showed strong enhancement. When compared with early phase images, delayed phase images of the same 13 lesions showed that enhancement was stronger in two lesions (15%), similar in six lesions (46%), and weaker in five lesions (38%).

CONCLUSION

On MRI, the typical appearance of inverted urothelial papillomas of the bladder is a polypoid shape with a nonpapillary surface and a thin short stalk surrounded by urine. Cystic foci are also occasionally seen within the tumor.

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.

Inverted Papilloma of the Prostatic Urethra Arising in a Juvenile

Inverted papilloma of the urinary tract is a rare benign lesion. We report, to our knowledge, the first case of inverted papilloma of the prostatic urethra arising in a juvenile. Our patient was referred for evaluation of painless, gross hematuria and voiding difficulty. Transrectal sonography demonstrated a 1.4 cm papillary lesion on the medial aspect of the prostatic urethra. Cystoscopy showed a solitary, papillary tumor on the prostatic urethra. Transurethral resection was performed and histological examination showed an inverted papilloma.

[Can inverted papilloma in urinary bladder be considered as a benign tumor]

Inverted papilloma of the urinary bladder is a rare entity. According to literature data, this disease is not malignant, and has low recurrence rate. Authors studied cases detected at the Urology Department and Urooncological Centrum at Semmelweis University in the last 11 years. They aimed to find out the rate of inverted papilloma recurrences, and transformations into malignant bladder cancer.

MATERIALS AND METHODS

Thirty patients with histologically proven inverted papilloma were followed after transurethral resection of bladder, which meant urine tests every three months, abdominal ultrasound and cystoscopy. After a year, these examinations were done in every six months.

RESULTS

Three patients presented transitiocellular carcinoma (17, 60, 92 months later) during this period. In one case, inverted papilloma and transitiocellular tumor (pTa G1) were detected. In one patient, inverted papilloma was found by control cystoscopy after transurethral resection of bladder (pT1 G2) and local chemotherapy 15 months later.

CONCLUSIONS

Based on authors' experience, inverted papilloma of the urinary bladder is a benign lesion, but malignant changes or concomitant transitiocellular tumor may occur, thus follow-up is needed. Although references are not standardized, authors suggest following patients with inverted papilloma as a primary (pTa G1) bladder cancer.

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

Inverted papilloma (IP) of the urothelium accounts for 2.2% of urothelial neoplasms. The aim of this study was to report the results of 13 patients with urinary IP, pointing out the clinical features, presentations, treatment options and outcomes. The mean age and mean follow-up periods of the patients were 60.23 +/- 3.25 (range, 44-81) years and 30 (range, 6-42) months, respectively. There was no coexistence of urothelial carcinoma with IP at presentation. Cystoscopy showed a solitary papillary tumor in the bladders of 11 patients and solid pedunculated tumors in the remaining two patients. The site of development was the bladder in 12 cases (92%) and ureter in one (8%) case. Transurethral bladder tumor resection was performed in 12 cases. For the case with IP in the ureter, nephroureterectomy was performed. Pathologic examination demonstrated that seven of the 13 cases were of the trabecular type and six were of the glandular type. Of the 13 cases, two (7%) had recurrence, at 1 year and 1 month and 1 year and 5 months from initial resection. The male to female ratio was 5.5:1. Initial symptoms included macroscopic hematuria in five cases, microscopic hematuria in four, and dysuria and microscopic hematuria in three; one case was asymptomatic. IPs of the urinary bladder are benign tumors that can be treated successfully by transurethral resection and fulguration of the tumor bed. In addition, these lesions must be followed up closely for recurrence and malignant transformation.

Low frequency of molecular changes and tumor recurrence in inverted papillomas of the urinary tract

AIM

Inverted papilloma (IP) of the urinary tract can be difficult to distinguish from noninvasive urothelial carcinoma with prominent inverted growth pattern (invNIUC). Ancillary markers may help to resolve such cases and clarify the reported malignant potential of some IPs.

METHODS

Eighty-nine urothelial lesions initially diagnosed as IP were reviewed by 4 experienced urologic pathologists and studied immunohistochemically (Ki67, p53, CK20, MSH2, MLH1, and MSH6). Mutations of the FGFR3 gene, deletions (loss of heterozygosity) of 9p, 9q, and 17p, microsatellite instability, and elevated microsatellite instability at selected tetranucleotides were also analyzed.

RESULTS

Considerable interobserver variability in histopathologic diagnoses was noticed. Only 62 (69.7%) initial diagnoses were confirmed by the review pathologists whereas 23 tumors (25.8%) were redefined as invNIUC. Molecular analyses revealed infrequent alterations in IPs, including microsatellite instability (1.8%), elevated microsatellite instability at selected tetranucleotides (13.2%), FGFR3 mutations (9.8%), 9p deletions (3.9%), 9q deletions (13.2%), 17p deletions (5.1%), nuclear p53 accumulation (18.9%), and aberrant immunostaining for MSH2 (5.8%), MLH1 (11.8%), and MSH6 (3.8%). IP and invNIUC differed in FGFR3 mutations and Ki-67 labeling index (P<0.001 each), and 9q loss of heterozygosity (P=0.03). There were fewer recurrences in IP (5.4%) compared with invNIUC (40.9%; P<0.0001).

CONCLUSIONS

IP is a benign lesion that lacks specific genetic alterations found in exophytic noninvasive papillary urothelial tumors. These lesions could be reactive in nature, perhaps secondary to chronic inflammation or a neoplastic process that lack specific genetic alterations. Nevertheless given the clinical and molecular data of this study a conservative clinical approach is appropriate.

Inverted urothelial papillomas with foamy or vacuolated cytoplasm

Inverted papillomas of the bladder are uncommon benign neoplasms characterized by endophytic growth of urothelial cells as anastomosing cords, displaying minimal cytologic atypia. Reports of inverted papilloma associated with urothelial carcinoma or urothelial carcinoma arising within inverted papilloma highlight the difficulties in evaluating urothelial lesions with inverted growth patterns. Within the spectrum of findings in inverted papilloma, vacuolization and foamy (xanthomatous-appearing) cytoplasmic changes have not been previously reported. In the current study, we present 5 novel cases of inverted papilloma involving 2 men and 3 women ranging in age from 48 to 88 years, who presented with microhematuria (n = 3) or irritative symptoms (n = 2). Cystoscopically, the lesions were polypoid (n = 3), pedunculated (n = 1), or solid (n = 1), measured between 0.7 and 2.5 cm, and were all located at the trigone or bladder neck. Morphologically, all cases had some component of usual inverted papilloma along with areas displaying foamy or vacuolated cytoplasm encompassing 30% to 90% of the lesion. These "clear cells" were seen both in distinct regions within the biopsy and, more frequently, intermingled with usual inverted papilloma cells. In 3 of 5 cases, these findings were sufficiently unusual to cause confusion with urothelial carcinoma. The diagnostic dilemma encountered in these cases of inverted papilloma with foamy or vacuolated cytoplasm warrants their distinction from other benign and malignant urothelial lesions with inverted growth and/or clear cell features.

Inverted papilloma of the urinary bladder: a molecular genetic appraisal

Inverted papilloma of urinary bladder is an uncommon urothelial neoplasm. Its relationship to urothelial carcinoma is controversial. Little is known of the genetic abnormalities of inverted papilloma. To better understand its genetics, we analyzed 39 inverted papillomas, including 36 from men and three from women, for loss of heterozygosity (LOH). We examined four polymorphic microsatellite markers located on chromosome 9q32-33(D9S177), chromosome 9p22 (IFNA), chromosome 3p14.2 (D3S1300) and chromosome 17p13.1 (TP53), where genetic alterations occur frequently in urothelial carcinomas. Additionally, the status of inactivation of X-chromosome was examined in three female patients. The frequency of LOH in informative cases was 8% (3 of 37) for D9S177, 10% (4 of 38) for TP53, 8% (3 of 37) for IFNA and 8% (3 of 36) for D3S1300. In the analysis of X-chromosome inactivation, all three cases yielded informative results and one had nonrandom inactivation of X-chromosomes. The monoclonal origin demonstrated in the study of X-chromosome inactivation indicates the clonal process of inverted papilloma; however, the low incidence of LOH supports the view that inverted papilloma in urinary bladder is a benign neoplasm with molecular genetic abnormalities different from those of urothelial carcinoma.

Inverted papilloma of urinary bladder: Is long-term cystoscopic surveillance needed? A single center’s experience

OBJECTIVES

To review all cases of urinary bladder inverted papilloma (IP) in our institution and determine the need for cystoscopic surveillance. IP is an uncommon benign tumor of the urinary tract. Its multiplicity, recurrence, and association with transitional cell carcinoma (TCC) suggest possible malignant potential, leading to conflicting clinical conclusions regarding the need for surveillance.

METHODS

All consecutive patients from January 1991 to December 2004 with IP were included in this study. A single pathologist performed the histologic review. The patients had undergone cystoscopy and ultrasound evaluation of the kidneys every 6 months.

RESULTS

Of the 52 patients, 45 were men and 7 were women. The average age at presentation was 58.9 +/- 11.8 years (range 30 to 79). No patient had a synchronous or previous bladder tumor. The most common complaint was macroscopic hematuria. Ten cases were incidental findings during bladder ultrasonography or cystoscopy. All were solitary tumors, most commonly found at the bladder neck. The average follow-up period was 62 +/- 23 months, with no recurrence. One case of subsequent noninvasive papillary TCC developed 15 months later. The initial histologic findings had revealed cytologic atypia, with suspicious urine cytology findings. On review, it was more compatible with TCC with an inverted pattern.

CONCLUSIONS

Although our cases exhibited benign biologic behavior, the presence of cytologic atypia and suspicious urine cytology require exclusion of TCC with an inverted pattern. Thus, in histologically proven solitary bladder IP with no associated TCC, cystoscopic surveillance may not be necessary.

Inverted Papillomas of the Prostatic Urethra

Inverted papillomas of the genitourinary tract are uncommon benign neoplasms usually occurring in the urinary bladder and less frequently in the upper urinary tract. To date, there are scant data and no comprehensive studies of inverted papilloma originating in the prostatic urethra. We identified 21 cases and evaluated their demographic, clinical, and histopathologic features. Patients had a mean age of 65.1 years (range: 30 to 89 y), with 10/21 (47.6%) presenting with gross hematuria (n = 8) or irritative symptoms (n = 2) related to the inverted papilloma and 11/21 (52.4%) detected incidentally during work-up/treatment of prostate cancer (n = 6) or benign prostatic hypertrophy (BPH) (n = 5). Fourteen cystoscopically evaluated lesions measured 0.1 to 2.0 cm, and were described as polypoid (n = 9), papillary (n = 4), or an enlarged median lobe (n = 1). Lesions were diagnosed on transurethral resection (n = 8), biopsy/polypectomy targeted to the lesion (n = 6), radical prostatectomy for prostate cancer (n = 4), or biopsy unrelated to the lesion (n = 3). Histologically, 14/21 cases (67%) displayed classic inverted papilloma architecture. The remaining cases showed foci of squamous metaplasia with moderate atypia (n = 4), rare true papillary fronds in a classic inverted papilloma background (n = 2), or both (n = 1). Eleven cases with prostatic tissue revealed adenocarcinoma of the prostate [n = 6; Gleason score 6 (n = 3) or 7 (n = 3)], high-grade prostatic intraepithelial neoplasia (n = 1), benign prostatic hypertrophy (n = 3), or adenosis (n = 1). No patients had a prior history of either inverted papilloma or urothelial carcinoma, whereas 2 patients were diagnosed with high-grade urothelial carcinoma of the bladder synchronous with their inverted papilloma diagnosis. Only 1 of the 18 patients with available follow-up had a recurrence of inverted papilloma in the prostatic urethra. None of the other patients had local recurrences or recurrences at other locations in the urinary tract (mean follow-up 39.9 mo; range: 3 to 120 mo). Inverted papillomas of the prostatic urethra are benign lesions that are commonly detected incidentally and are not associated with a history of urothelial malignancy. Although urothelial carcinoma elsewhere in the genitourinary tract may occur simultaneously, malignant transformation or recurrence as a malignant lesion has not been identified in inverted papilloma of the prostatic urethra.

Natural history of urothelial inverted papilloma

BACKGROUND

Inverted urothelial papilloma is an uncommon urothelial neoplasm. Although it is traditionally regarded as a benign tumor, conflicting data on multiplicity, recurrence rate, and association with urothelial carcinoma have left uncertainties concerning its biologic behavior.

METHODS

The authors analyzed the clinicopathological characteristics of 75 cases of inverted papilloma in the urinary tract without prior or concurrent urothelial carcinoma to determine its biologic behavior and prognosis, and to correlate these findings with surveillance strategies.

RESULTS

These patients ranged in age from 26 to 85 years (mean, 60 years). Of the 46 patients for whom tobacco use history was available, 28 gave a history of smoking. Inverted papillomas were located in the urinary bladder (67 cases), prostatic urethra (4 cases), and ureter (4 cases). The majority of vesical tumors arose from the trigone or near the bladder neck. Common presenting complaints included hematuria, dysuria, and irritative voiding symptoms. In 1 case of vesical inverted papilloma, there was a recurrence. All other patients were free of tumor recurrence or progression during a mean follow-up of 68 months (range, 2-240 months).

CONCLUSIONS

Both the extremely low incidence of tumor recurrence (1%) and strikingly favorable prognosis suggest that inverted urothelial papilloma, when diagnosed according to strictly defined criteria, is a benign urothelial neoplasm not related to urothelial carcinoma. Therefore, complete transurethral resection of inverted papilloma is adequate surgical therapy, and surveillance protocols as rigorous as those employed in the management of urothelial carcinoma seem unnecessary.

Synchronous inverted papilloma of bladder and renal pelvis

Inverted papilloma of the urinary tract is a rare tumor that consists of uniform urothelial cells with an inverted configuration and a normal urothelial lining. Despite several published reports, the prognostic significance and the potential biologic behavior remain uncertain. We detail a case of synchronous inverted papilloma of the urinary bladder and the renal pelvis and review the published data.

IS SURVEILLANCE NECESSARY FOR INVERTED PAPILLOMA IN THE URINARY BLADDER AND URETHRA?

BACKGROUND

A case series of inverted papilloma of the urinary bladder and urethra is presented, together with a review of the literature with respect to multiplicity, recurrence rate and association with transitional cell carcinoma, and a discussion on surveillance of the lesion.

METHODS

Cases of inverted papilloma of the lower urinary tract in a single centre were reviewed. Patient and tumour characteristics, recurrence and associated transitional cell carcinoma are reported.

RESULTS

Twenty patients were included (18 male, two female). The mean age was 60.8 years (range 35-78 years). All had solitary tumours ranging from 3 mm to 30 mm in size. Median cystoscopic follow up was 30 months (range 2-140 months). There was no recurrence. One patient was associated with subsequent transitional cell carcinoma 44 and 76 months later. Together with the present 20 cases, review of the English literature with respect to inverted papilloma of the lower urinary tract identified a total of 322 cases reported, with a recurrence rate of 3.85%. Moreover, 1.55%, 5.90% and 1.54% were associated with previous, simultaneous and subsequent transitional cell carcinoma, respectively.

CONCLUSIONS

Recurrence is not uncommon and risk of subsequent transitional cell carcinoma is not rare, such that non-invasive surveillance with flexible cystoscopy is recommended for inverted papilloma of the lower urinary tract.

Papiloma invertido vesical con recidiva en uretra prostática

Urothelial inverted papilloma is usually a solitary lesion with rare recurrences. Its behaviour is unclear, its potential for recurrence or progression is not well-known. We present a case of inverted papilloma of the bladder with recurrence in prostatic urethra after four years of follow-up. We review etiology, clinical presentation, diagnose, treatment and the present discussion about its malignancy ability.

Atypia in inverted urothelial papillomas: Pathology and prognostic significance

Inverted papillomas of the bladder are considered benign urothelial neoplasms, based on their histology and clinical course. There are scant data on inverted papillomas with atypical features. Whether to designate them as inverted papillomas with atypia or low-grade transitional cell carcinomas with inverted features is controversial. In the present study, 11 cases of inverted papillomas with atypia and 10 controls of classic inverted papillomas without atypia were collected from 2 institutions. The inverted papillomas with atypia had the typical architectural features of inverted papillomas consisting of thin anastomosing trabeculae of urothelium growing downward into the stroma without an exophytic papillary component. The atypical areas in the current series were focal, with other areas exhibiting the benign cytology of classic inverted papillomas. Cases with atypia were subdivided into the following groups: (1) 5 cases notable for areas containing prominent nucleoli, (2) 2 cases with foci with atypical squamous features, (3) 2 cases with areas of dysplasia, approaching the level of carcinoma in situ, (4) 1 case with degenerative-appearing multinucleated giant cells, and (5) 1 case notable for nests of atypical squamous cells associated with large, atypical squamoid cells with a pagetoid appearance in addition to degenerative-appearing multinucleated giant cells. Ki67 was slightly increased in 1 case, with focal dysplasia approaching carcinoma in situ and in 1 case with prominent nucleoli (increased Ki67 in both the atypical and non-atypical areas) and in the case with atypical squamous, pagetoid, and giant cells (no increased Ki67 in the atypical components). Two of the atypical inverted papilloma cases with prominent nucleoli demonstrated an increase in p53 staining throughout the lesions. Cytokeratin (CK) 20 staining was negative in all cases of inverted papillomas. No significant increase in Ki67 staining was found in any of the 10 control cases; increased p53 staining was seen in 1 control case. CK20 staining was negative in the 10 control cases. In the 11 cases with atypia, clinical follow-up revealed no history of prior or subsequent bladder neoplasms. In the cases reviewed, most inverted papillomas with atypia did not demonstrate significantly increased cellular proliferation in comparison with inverted papillomas without atypical features. To date, there has been no association with urothelial carcinoma in the individuals diagnosed with atypical inverted papillomas. These findings suggest that these lesions are currently best classified as inverted papillomas with atypia, not as low-grade transitional carcinomas, and that they merit continued evaluation as a distinct group.

Phenotype of columnar-lined esophagus in rats with esophagogastroduodenal anastomosis: similarity to human Barrett's esophagus

In rats, esophagogastroduodenal anastomosis (EGDA) without concomitant chemical carcinogen treatment can lead to columnar-lined esophagus (CLE) including metaplasia, dysplasia, and esophageal adenocarcinoma (EAC). This study describes the morphology and phenotypic features of CLE and EAC in the rat model and compares them with the corresponding lesions in human Barrett's esophagus (BE). Swiss roll preparations of esophagi of EGDA rats and biopsies from human BE containing specialized intestinal metaplasia (SIM) and EAC were examined. The esophagi of EGDA rats showed esophagitis, CLE, islands of multilayered epithelium (MLE), dysplasia and EAC. The CLE had features of specialized intestinal metaplasia. MLE frequently occurred at the neo-squamocolumnar junction and occasionally in the mid-esophagus in isolated foci. Scattered mucinous cells in esophageal squamous epithelium were also found. The CLE and MLE in EGDA rats resembled the lesions described in human BE in morphology, mucin features and expression of differentiation markers (CK7, CK20, Das-1, villin, and pS2/TFF1). Invasive EAC in EGDA rat is of well-differentiated mucinous type, which is in contrast to the variably differentiated glandular type of adenocarcinoma in human BE. p53, c-myc, and cyclooxygenase 2 are expressed in both the rat and human SIM and EAC. These studies indicate that, not withstanding small differences, SIM and EAC induced in EGDA rats are similar to the corresponding lesions in human BE. EGDA rats may serve as a useful model to study the pathogenesis, molecular biology, and chemopreventive interventions of human BE and EAC.

[Inverted papillomas--cases at our service and review of the literature]

Inverted papillomas are rare tumours representing about 2.2% of all urothelial tumours (benign or malignant). Inverted papillomas are predominantly seen in the bladder but these tumours have also been described in other locations, all over the urinary tract. The authors report six additional cases of such tumours describing the individual characteristics of each case, presenting symptoms, treatment employed and follow up available. A review of the literature relative to aetiology, clinical signs and symptoms, diagnostic criteria, treatment options and outcome has also been carried out.

Histopathologic and biologic characteristics of a transitional cell carcinoma with inverted papilloma-like endophytic growth pattern

To evaluate histopathologic and biologic characteristics in a patient with transitional cell carcinoma (TCC) with an endophytic growth pattern similar to that seen in an inverted papilloma. Although the tumor surface was mostly covered with normal-looking urothelium, the covering layer was thicker in parts than in those of benign papillomas. The widths of the trabeculae were irregular, and cytologic atypia with remarkable mitosis was seen. High expression of p53, Ki67, and cytoplasmic cyclin D1 was demonstrated by immunohistochemical staining. To clarify the biologic activities of tumors with inverted papilloma-like growth pattern, even when it appears as benign lesions by routine pathologic examination, analyses of immunoreactivity for proliferation markers might be critical.

The nested variant of urothelial carcinoma: a rare but important bladder neoplasm with aggressive behavior. Three case reports and a review of the literature

OBJECTIVE

To describe our experience with the nested variant of urothelial carcinoma (UC-NV) of the bladder, by characterization of the clinical picture and the prognostic implications of this rare form of bladder neoplasm.

MATERIALS AND METHODS

Three cases of UC-NV of the bladder treated in our institutions were revised and data compared with previously published case-reports.

RESULTS

Three patients presented with advanced muscle-invasive UC-NV, of which two had lymph node metastasis at cystoprostatectomy. The histopathology in the latter two cases showed the same picture in the lymph node metastasis as in the primary tumor with nests of tumor cells with mild-moderate atypia. In all three cases the tumor involved a ureteric orifice or the bladder neck.

CONCLUSION

UC-NV is a rare but important histopathologic entity. It has a poor prognosis. At early stage, tumors might be difficult to differentiate from benign conditions and awareness of the condition is of outermost importance.

Inverted papilloma as a cause of high-grade ureteral obstruction

Inverted papilloma of the urinary tract is a rare benign lesion. We report, to our knowledge, the first case of high-grade ureteral obstruction caused by an inverted papilloma with coexistent carcinomatous elements. Our patient was referred for evaluation of painless, gross hematuria. Imaging studies demonstrated a left proximal ureteral filling defect causing severe left-sided hydroureteronephrosis. Ureteroscopy demonstrated a 1-cm papillary lesion on the medial aspect of the proximal ureteral wall. Pathologic examination documented a lesion with elements of inverted papilloma and a small focus of well-differentiated transitional cell carcinoma. We discuss the management and significance of this rare urothelial lesion.

[Inverted papilloma of the prostatic urethra]

The inverted papilloma is a rare urothelial tumor, and its localization at the prosthatic urethra is also exceptional. We present a case of inverted papilloma of the prostatic urethra in a 72 years-old male, with symptoms of urinary flow obstruction. The diagnose is obtained after urethrocistoscopy and transurethral resection at the same time. We discuss about the etiology, clinical presentation, diagnose and treatment of this rare tumor, making special attention to its malignancy ability.

Inverted urothelial papilloma: is ploidy, MIB-1 proliferative activity, or p53 protein accumulation predictive of urothelial carcinoma?

BACKGROUND

Inverted urothelial papilloma is an unusual neoplasm of the urinary tract. Although the association between inverted urothelial papilloma and urothelial carcinoma is not entirely clear, many studies indicate that patients with inverted papilloma are at increased risk for the development of urothelial carcinoma. In addition, aneuploid inverted papillomas have been associated with the subsequent development of urothelial carcinoma. The objective of this study was to determine whether ploidy, MIB-1 proliferative activity, or p53 protein staining in inverted papilloma were predictive of urothelial carcinoma.

METHODS

Fifty-one cases of inverted papilloma were retrieved from the Tissue Registry of the Mayo Clinic. Clinical records were reviewed for patient age, length of follow-up, and history of urothelial carcinoma (defined as carcinoma prior to, concurrent with, or subsequent to the diagnosis of inverted papilloma). DNA ploidy analysis was determined using Feulgen stained sections from paraffin embedded tissues using an image analysis system. Quantitation of MIB-1 proliferative activity and p53 immunostaining was determined similarly using immunoperoxidase stained sections from paraffin embedded tissues.

RESULTS

The mean age at diagnosis of inverted papilloma was 63.9 years (range, 37-87 years), and there were 39 men and 12 women. Patients were followed for a mean of 56.5 months (range, 1-252 months). Tumors ranged in size from 0.2 to 4.3 cm (mean, 0.9 cm). Eight patients (15.7%) had a prior, concurrent, or subsequent noninvasive World Health Organization and International Society of Urologic Pathology (WHO/ISUP) papillary neoplasm of low malignant potential or papillary carcinoma of low grade (formerly WHO Grade 1 or 2 papillary urothelial carcinoma). Inverted papillomas in patients with a history of urothelial carcinoma were all diploid and had a mean MIB-1 activity of 6.3% (range, 0.04-24.8%) and mean p53 protein staining of 12.6% (range, 0.5-24.9%). These inverted papillomas ranged in size from 0.3 to 1.0 cm (mean, 0.5 cm). Inverted papillomas in patients without a history of urothelial carcinoma were aneuploid in 6 cases (14.3%) and diploid in the remaining cases. These inverted papillomas had a mean MIB-1 activity of 1.6% (range, 0.06-9.0%) and mean p53 protein staining of 9.7% (range, 0.05-38.0%). Tumor size ranged from 0.2 to 4.3 cm (mean, 1.0 cm). There were no statistically significant differences in MIB-1 activity, p53 protein staining, ploidy, and morphologic features between inverted papillomas in patients with and without a history of urothelial carcinoma.

CONCLUSIONS

Ploidy, MIB-1 proliferative activity, and p53 immunostaining in inverted urothelial papilloma were not useful in identifying patients who had a history of urothelial carcinoma.