Inverted papilloma of the lower 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.

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 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.

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.

Clinical Studies on Inverted Papilloma of the Urinary Tract: Report of 48 Cases and Review of the Literature

PURPOSE

We report on 48 clinicopathologic cases of inverted papilloma and present the clinical significance attributed to these lesions in terms of the current literature.

MATERIALS AND METHODS

From 1976 to 2002 we had experience with 48 cases of inverted papilloma in urinary tract. We present the clinical features of these cases and report the results of prognosis research.

RESULTS

Patient age ranged from 24 to 82 years (mean 56). Coexistence of transitional cell carcinoma occurred in a different location in the bladder in 3 cases and within a single neoplasm in the ureter in 2. Followup data were available in 42 of the 48 cases. Followup ranged from 8 months to 23 years 6 months (mean 8 years 1 month). Of the 42 cases 3 (7%) had a recurrence and range from initial resection at 5 months, 1 year 4 months and 2 years 6 months, respectively.

CONCLUSIONS

Our study suggests that there are 2 types of urinary inverted papilloma. The lesions in 1 type behave in a benign fashion and in another they have malignant potential. At this time we have no strategy with which to distinguish the 2 types of urinary inverted papilloma. Our results indicate that we must follow all cases for at least more than 2 years after initial treatment.

The nested variant of the transitional cell bladder carcinoma: a case report and review of the literature

The nested variant of transitional cell carcinoma is extremely rare in the bladder. Here we reported a new case and review the literature.

Diagnosis and grading of bladder cancer and associated lesions

Standardized classification and grading of urothelial carcinoma has now been achieved internationally. Uniformity of pathologic reporting should improve the comparability of different studies and therapies and provide more accurate information to urologists in managing patients.

Bulky transitional cell carcinoma of bladder with inverted proliferation

Two women, aged 51 and 62 years, had unusual transitional cell carcinomas of the urinary bladder which were > 5 cm and had a structural resemblance to inverted papilloma or Brunn's nest. They were treated by bladder-preserving surgery with no evidence of recurrence after 30 and 103 months follow-up, respectively. Our cases show some hitherto unrecognized aspects of transitional cell carcinoma with inverted proliferation because the tumors are usually found in males and tend to be aggressive.

II Papilloma Invertito Dell'uretra Prostatica: Nostra Esperienza e Revisione Della Letteratura

The inverted papilloma is a rare polipoid lesion of urothelial origin and unknown etiopathogenesis. Since 1963 more than 100 cases have been reported. We describe a case of inverted papilloma of the bladder neck and prostatic urethra. The association with transitional cell carcinoma of the bladder, the potential for recurrence and therapeutic treatment are considered.

A case of inverted papilloma of the ureter: is the DNA ploidy pattern associated with occurrence of transitional cell carcinoma of the bladder?

We describe herein a case of inverted papilloma of the ureter, in which transitional cell carcinoma of the bladder developed twenty-three months after nephroureterectomy. Flow cytometric analysis of formalin-fixed and paraffin-embedded archival material of the inverted papilloma revealed DNA aneuploidy pattern and relatively high percentage of S phase. Retrospectively, DNA measurement thus provided the predictive value regarding biological activity and the clinical behaviour of the present case.

Unusual forms of carcinoma of the urinary bladder

Carcinomas of the urinary bladder, which differ histologically from the usual transitional cell carcinoma of the bladder, are reviewed. These tumors, which account for approximately 15% of all bladder carcinomas, have diverse microscopic appearances. They fall into four major categories: variant forms of urothelial (transitional cell) carcinoma, squamous cell carcinoma, adenocarcinoma, and undifferentiated carcinoma. In the first category, the most common are carcinomas with glandular or squamous differentiation. Less common, but more troublesome diagnostically, are variants in which the cells are spindle shaped (sarcomatoid carcinoma), form small cysts (microcystic carcinoma), or differentiate toward trophoblast. In other variants, the stroma has unusual features that may lead to diagnostic difficulty. These are carcinomas with pseudosarcomatous stroma, osseous or cartilaginous metaplasia, or osteoclast-type giant cells. Also reviewed are squamous cell carcinoma and its variant, verrucous carcinoma. Vesical adenocarcinoma has several variants, including signet-ring cell and clear cell types. Finally, the category of undifferentiated carcinoma, including small cell carcinoma, giant cell carcinoma, and lymphoepithelioma-like carcinoma, is discussed.

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.

Urothelial carcinoma occurring within an inverted papilloma of the ureter

Only 5 cases of inverted papilloma of the ureter with a malignant component have been reported previously. We add case 6 to the literature. The incidence of concomitant malignancy in ureteral inverted papillomas is 3 times that found in similar lesions occurring in the bladder.

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 the urinary tract: histogenesis, recurrence and associated malignancy

We describe 5 new cases of inverted papilloma of the urinary tract. One case represents the second known recurrence of this tumor while another demonstrated areas of adjacent low grade papillary transitional cell carcinoma. Immunohistochemical studies suggest a histogenetic difference between inverted papillomas of the prostatic urethra and of the bladder.

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 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.

The association of inverted papilloma and transitional cell carcinoma of the urothelium

Inverted papilloma generally is considered a benign lesion, with recurrence documented in only 1 case. However, the association of typical transitional cell carcinoma and inverted papilloma in a single lesion has been reported rarely. We present 1 such case and review the literature. Treatment recommendations are included.

Inverted papilloma of ureter

A rare case of inverted papilloma of the ureter in a sixty-eight-year-old man is presented, and the literature is reviewed.

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 of the urinary tract

We report 9 clinicopathological cases of inverted papilloma. The occurrence of associated true malignant epithelial tumors in the urinary tract in 4 patients is not concurrent with previous reports. Even though inverted papilloma per se is a benign lesion it may be associated with malignant epithelial tumors of the urinary tract. The similarity between proliferative lesions of the bladder and inverted papilloma is discussed. The possibility of common etiologic factors of proliferative cystitis, cystitis cystica, cystitis glandularis, inverted papilloma and ordinary bladder tumors may be considered.