Inverted papilloma of the urinary tract

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.

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.

[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.

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.

Case report: laparoscopic resection of ureteral inverted papilloma

Inverted papilloma of the ureter is a rare entity, often mistaken for malignancy during work-up. As such, many of these patients have been unnecessarily treated with nephroureterectomy. Herein, we describe a novel laparoscopic approach for the treatment of a ureteral inverted papilloma. To our knowledge, this approach is the first application of laparoscopy for the treatment of this lesion.

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.

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.

[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.

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 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.

Upper urinary tract inverted papillomas

Inverted papilloma is a rare, benign tumor. Only 33 cases to date have been reported to have occurred in the upper urinary tract. These lesions have a male predominance, are difficult to diagnose, and are associated with urothelial malignancy. Because transitional cell carcinoma can present even 8 years after surgery and in other sites within the urinary system, careful follow-up is essential. This article adds 2 new cases and 1 follow-up of a previously reported case from 1990.

Urothelial transitional cell carcinoma with endophytic growth patterns: a discussion of patterns of invasion and problems associated with assessment of invasion in 18 cases

Most papillary transitional cell carcinomas (TCC) are characterized architecturally by an exophytic growth of fingerlike papillae, but some exhibit a prominent endophytic growth pattern resulting in considerable difficulty in assessing invasion. We report on 18 cases of TCC (17 urinary bladder, one pelvicalyceal system) in which endophytic growth was evident either as interanastomosing cords and columns of urothelium, often with a striking resemblance to inverted papilloma (inverted papilloma-like pattern), or as broad, pushing bulbous invaginations into the lamina propria (broad-front pattern). The mean age of the patients was 68 years (range, 32-94 years), with a male preponderance (3.5:1). In four cases, the endophytic pattern was exclusively inverted papilloma-like, 10 cases had only the broad-front pattern, and four cases showed both patterns. Exophytic papillary TCC of the usual type was present in all but two cases, varying from focal (five cases) to moderate (five cases) to extensive (six cases). In spite of the extensive incursion into the lamina propria resulting from the inverted growth, only nine cases (50%) had unequivocal destructive invasion (lamina propria invasion, eight cases; muscularis propria invasion, one case). Follow-up data, available in 14 cases (1-48 months; mean, 15.5 months), revealed one patient alive with disease, 11 patients with no evidence of disease, and two patients dead of other causes. The limited follow-up does not permit evaluation of the impact of the endophytic patterns on outcome. Because the phenomenon of endophytic growth in TCC has received little attention, we present detailed morphologic descriptions of our cases and review the problems associated with assessment of invasion and the different patterns of invasion by TCC.

Multifocal, synchronous inverted papillomas involving the ureter

Inverted papillomas involving the upper urinary tract remain a rarely diagnosed phenomenon. A case of bilateral ureteral inverted papillomas is presented. The treatment and diagnosis of this lesion remain a challenge.

Bilateral ureteral inverted papillomas in association with bladder carcinoma: a case report and review of the literature

A case of multiple inverted papillomas of both ureters, in association with a bladder carcinoma, is presented. Inverted papilloma is a rare benign urothelial tumor. Because of its curability by conservative surgery, it should be considered in the differential diagnosis of a ureteral filling defect and ureteral obstruction. Inverted papilloma may be associated with carcinomas of the urinary tract.

Inverted papilloma of renal pelvis: flexible ureteroscopic diagnosis and treatment

A case is reported of inverted papilloma of the renal pelvis in a patient with previous transitional cell carcinoma of the bladder. The renal pelvic lesion was diagnosed and treated with a flexible ureteropyeloscope. Although nephroureterectomy was avoided, the patient must be carefully followed endoscopically and radiographically for recurrence of lesions throughout the urinary tract. This case represents the first report of the endoscopic diagnosis and treatment of an inverted papilloma of the renal pelvis. It demonstrates the vast potential for endoscopic diagnosis, treatment, and surveillance throughout the urinary tract.

Inverted papilloma of the ureter with malignant change

Three patients with inverted papilloma of the ureter are described. A range of histological features was seen, including one showing malignant change. This condition, which is probably more common than previously thought, can be successfully treated by conservative surgery and close follow-up.

Multiple simultaneous inverted papillomas of the upper urinary tract. A case report with a review of ureteral and renal pelvic inverted papillomas

An asymptomatic 73-year-old woman was found to have multiple, simultaneous, inverted papillomas of the renal pelvis and ureter. A review of the world literature yielded 34 cases of inverted papillomas in the upper urinary tract: 13 in the renal pelvis, and 21 in the ureter. Among these 34 cases, there were 26 male and five female patients, with gender not given for three others. Patients ranged in age from 19 to 89 years (mean, 64.1 years). Many cases lacked complete clinical details but, among the others, gross painless hematuria was the presenting symptom in seven; hematuria with flank pain or colic in six; and pain without hematuria in six. Only six patients lacked urinary tract symptoms, and three of these had microscopic hematuria. Only two patients had more than one inverted papilloma, and these were not multicentric. Adequate pathologic documentation and follow-up data were, unfortunately, absent in many of the cases. Although inverted papillomas are curable with surgical resection, with a low rate of local recurrence, they appear to be associated with synchronous or asynchronous carcinomas, especially other transitional cell tumors in the urinary tract.

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 renal pelvis associated with contralateral ureteral malignancy and bladder recurrence

We report a case of an inverted papilloma of the renal pelvis diagnosed at the same time as transitional cell carcinoma of the contralateral ureter. The diagnostic studies and surgical management are presented. Recurrence of an inverted papilloma in the bladder 1 year after treatment was confirmed histologically. Recurrence of this lesion and the association with urothelial malignancy suggest the need for close followup of patients with an inverted papilloma.

Inverted papilloma with intussusception of the ureter. Case report

A case of inverted papilloma with intussusception of the ureter is reported. The patient is followed up 5 years after conservative treatment by partial resection of the ureter. No signs of urothelial tumor in the upper urinary tract or urinary bladder were revealed.

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.

Inverted papillomas of the urinary tract. A case of multiple, recurring inverted papillomas of the renal pelvis, ureter and bladder associated with malignant change

A case of multiple, recurring urothelial inverted papillomas is reported with localization in the bladder, ureter and renal pelvis. Association of several of these with areas of transitional cell tumours and final occurrence of pure transitional cell tumour of papillary and non-papillary type grade II, causes us to question the original concept of inverted papillomas as benign tumours and lean to the more recent concept of inverted papillomas representing precancerous lesions.

Treatment of urothelial tumors of the upper urinary tract by nephroureterectomy, renal autotransplantation, and pyelocystostomy

Nephroureterectomy, renal autotransplantation, and pyelocystostomy have been performed in eight patients with urothelial tumors of the upper urinary tract. One patient had tumors in a solitary kidney, two patients had bilateral tumors, and five patients had unilateral tumors. Three patients have had recurrent calyceal tumors which were successively managed by the transurethral route. In one patient the kidney had to be removed after 4.5 years because of infiltrating tumor recurrence. Two patients died; the renal pelvis of the graft was tumor free at autopsy in both cases. The other five patients are alive and free from tumor recurrence. The procedure implies increased radicality compared with conventional conservative treatment and simplified follow-up. It may be considered in patients with bilateral tumors or tumors of a solitary kidney, and in selected patients with unilateral low-grade, low-stage tumors.