Adenomatous metaplasia (nephrogenic adenoma) of urothelium. An analysis of 70 cases

p16 Immunohistochemical Expression in Nephrogenic Adenoma

Nephrogenic adenoma (NA) is a rare metaplastic entity commonly associated with a prior urothelial injury. Most are seen in the urinary bladder and a minority involve the urethra. In this study, we evaluated the expression of p16 as a surrogate marker of this entity and correlated it with clinical pathological parameters. A total of 17 cases of NA were retrospectively studied to assess the immunohistochemical expression of p16 and its value for the diagnosis of this entity.

Napsin A is a highly sensitive marker for nephrogenic adenoma: an immunohistochemical study with a specificity test in genitourinary tumors

Nephrogenic adenomas are uncommon benign lesions that are typically cytologically bland, but degenerative and reactive changes may make it difficult to distinguish these lesions from malignant entities, such as urothelial carcinoma and prostatic adenocarcinoma. In this study, we explored whether napsin A, a sensitive marker for lung adenocarcinoma, may also have a role in distinguishing nephrogenic adenoma from other genitourinary lesions. Immunohistochemically, napsin A was expressed in all 43 nephrogenic adenomas (bladder: 38, prostatic urethra: 4, and ureter: 1; mean positive tumor cells: 72%, median: 80%, range: 15-100%) and showed regional variability in its expression pattern with a bias toward surface architectures (flat, papillary) compared with stromal architectures (tubular/glandular, microcystic). We also compared napsin A with other markers including PAX8, GATA3, p63, and 34BE12. Although napsin A matched PAX8 in terms of its sensitivity for nephrogenic adenoma (100%), napsin A stained a lower percentage of tumor cells than PAX8 (72% vs 99%, respectively, P = 1.0 × 10^-5). P63 was negative in all nephrogenic adenomas, whereas GATA3 showed variable staining in 25 cases (58%). All 43 nephrogenic adenomas showed variable 34BE12 staining. Finally, we profiled napsin A expression among 401 genitourinary tumors on tissue microarrays (n = 308) and full tissue blocks (N = 93) and observed napsin A positivity in 37 tumors (9%), which included urothelial carcinomas with the glandular/microcystic component differentiation (in the glandular/microcystic component in 4/6), bladder adenocarcinomas (primary: 4/4 and metastatic: 3/3), urinary tract clear-cell carcinomas (primary: 8/9, metastatic uterine primary: 1/1), and some renal tumors (17/174). All 81 pure urothelial carcinomas and 53 prostatic acinar adenocarcinomas were negative for napsin A. Our study indicates that napsin A is a highly sensitive marker for nephrogenic adenoma and can serve as a useful addition in immunohistochemical panels seeking to distinguish it from pure urothelial carcinoma and prostatic acinar adenocarcinoma but not clear-cell carcinoma or urothelial carcinoma with glandular differentiation.

In vivo replacement of damaged bladder urothelium by Wolffian duct epithelial cells

The bladder's remarkable regenerative capacity had been thought to derive exclusively from its own progenitors. While examining consequences of DNA methyltransferase 1 (Dnmt1) inactivation in mouse embryonic bladder epithelium, we made the surprising discovery that Wolffian duct epithelial cells can support bladder regeneration. Conditional Dnmt1 inactivation in mouse urethral and bladder epithelium triggers widespread apoptosis, depletes basal and intermediate bladder cells, and disrupts uroplakin protein expression. These events coincide with Wolffian duct epithelial cell recruitment into Dnmt1 mutant urethra and bladder where they are reprogrammed to express bladder markers, including FOXA1, keratin 5, P63, and uroplakin. This is evidence that Wolffian duct epithelial cells are summoned in vivo to replace damaged bladder epithelium and function as a reservoir of cells for bladder regeneration.

Nephrogenic adenoma of the bladder: a single institution experience assessing clinical factors

Introduction:

Nephrogenic adenoma (NA) was first described by Davis in 1949 as a “hamartoma” of the bladder. There are many proposed predisposing factors for NA including chronic inflammation, renal transplantation, and bladder cancer. We examined our experience with NA to determine predisposing factors and determine if there was any increased risk for development of subsequent malignancy.

Materials and Methods:

All patients with a pathologic diagnosis of bladder NA from 2001-2013 were included. Patient history, clinical factors including possible predisposing factors for NA, and follow-up were reviewed.

Results:

Among 60 patients, 68% were males with an average age of 61, an average BMI of 28.7, and 60% had a smoking history. In evaluating pro-inflammatory factors, 26.7% underwent either Bacillus Calmette-Guerin or mitomycin C, 30% had recurrent urinary tract infections, and 25% had a history of catheterization. Recurrence of NA after initial resection occurred only in 14.7% of patients who underwent follow-up cystoscopy. A history of concurrent bladder cancer was seen in 41.7% of patients, but there were no cases of de novo bladder cancer diagnosed after NA.

Conclusion:

To the best of our knowledge, this is the largest series of patients with NA of the bladder. NA occurs in a heterogeneous population of patients, but most often with underlying inflammation. NA occurred concurrent with bladder cancer; however there were no cases of de novo bladder cancer after NA, reassuring that NA is likely a benign reactive condition.

Recurrence of childhood nephrogenic adenoma in urinary bladder developed four years after previous surgery despite intravesical sodium hyaluronate therapy

Nephrogenic adenoma (NA) is a rarely seen benign metaplastic lesion of the urinary tract. Its etiology is uncertain, but induced by chronic inflammation, irritation, and trauma. NA is located in the urinary tract, most commonly in the bladder. NA usually presents with hematuria and lower urinary tract symptoms. In the literature it is mostly seen in adults but about 30 cases of NA's have been reported in children. Treatment of intravesical lesions consists of transurethral resection (TUR) and fulguration and rarely partial or total cystectomy may be required in ineffective TUR. Recurrence rate is high during long-term follow-up. The intravesical application of sodium hyaluronate produces a protective effect on the glycosaminoglycan layer and delays or prevents its recurrence. We report a case of recurrent NA of the bladder in a pediatric male patient who was presented four years after previous surgery despite intravesical sodium hyaluronate therapy.

Metaplastic Conditions in The Bladder in Patient with Epidermolysis Bullosa

Epidermolysis bullosa is a rare inherited muco-cutaneous disorder that sometimes presents with genitourinary involvement. Herein we report the case of an 11-year-old girl with a history of junctional epidermolysis bullosa who was admitted with urological symptoms. On cystoscopy, suspected bullous bladder lesions were observed. Mesonephroid, intestinal and squamous metaplasia is reported here for the first time.

Nephrogenic adenoma in elderly patients: Three case reports

Nephrogenic adenoma (NA), referred to as nephrogenic metaplasia, is a rare benign lesion of the urinary tract. NA is histologically characterized by tubular and papillary formations lined by low cuboidal to columnar epithelial cells. NA is also immunohistochemically characterized by positivity for paired box (PAX) 2, PAX8 and cytokeratin 7, and negative for p63 and prostate-specific antigen. In this study, we present 3 cases of NA arising in the urinary bladder of elderly male patients with predisposing factors: patient 1 had undergone transurethral lithotripsy due to a ureteral stone; patient 2 had undergone transurethral resection of a urothelial carcinoma in the urinary bladder; and patient 3 had been treated with Bacillus-Calmettle-Guérin due to a urothelial carcinoma in the urinary bladder. The characteristics of the NAs of our 3 cases were histologically and immunohistologically consistent with previously reported cases, although 1 patient exhibited a pseudoinvasive pattern. Since NA is a tumor-like benign lesion, it should be clearly differentiated morphologically and immunohistologically from other tumors arising in the urinary tract and from invasion by prostate cancer.

Adenomatous Metaplasia Arising in a Horse-Shoe Kidney - A Rare Entity

Urinary adenomatous metaplasia (nephrogenic adenomas) is uncommon, benign, apparently metaplastic response of the urothelium to chronic inflammation, trauma, surgery, urolithiasis, long-term indwelling urethral catheterization, and immunosuppressive therapy instillation. Gross or microscopic hematuria and some irritable urinary tract symptoms are often observed. A diagnosis is primarily based on the histopathological examination. We are reporting this case because adenomatous metaplasia is very rarely reported in the kidney especially in a horse shoe kidney with a large renal stone and these lesions could be mistakenly diagnosed as malignancy. In our knowledge this is the very first case of its kind. An awareness of this entity is critical to prevent over-diagnosis of cancer and to avoid unnecessary treatment.

Primary Urethral Plasmacytoma Treated with High-Dose-Rate Brachytherapy: A Case Report

Primary urethral solitary plasmacytoma is a very rare variant of extramedullary plasmacytoma. In total, only 9 cases have been reported so far. Patients were treated either by surgery or by external radiation therapy. Here, we report on a 22-year-old man, initially presenting with a palpable induration at the penis, intermittent dysuria and haematospermia, which was due to histologically confirmed solitary urethral kappa-restricted plasmacytoma. The patient subsequently underwent percutaneous and endo-urethral high-dose-rate brachytherapy with a total dose of 42 Gy applied in 14 fractions. Besides an uncomplicated urinary tract infection and hyperpigmentation of the penis, the patient tolerated the radiotherapy well and is still free of disease after 15 months follow-up.

Fibromyxoid nephrogenic adenoma protruding in a renal cortical cyst. A rare morphological variant in an outstanding location

Nephrogenic adenoma (NA) is an unusual, benign lesion of the urinary tract, generally presenting in the bladder and with less frequency in the renal pelvis, urethra or ureter. It consists of tubules, microcysts and papillae lined by a single layer of low cuboidal epithelium without atypia. Recently, a fibromyxoid variant mimicking an infiltrating mucinous adenocarcinoma has been described. We report hereby the case of a 70-year-old female with a fibromixoid NA protruding in a renal cortical cyst. Only one case of NA in a renal cortical cyst has been found in the literature and it was of the classical type. The development of a NA in a renal cortical cyst lends support to the theory that the NA results from proliferation of secondarily implanted exfoliated renal epithelial cells.

Syringometaplasia: variants and underlying mechanisms

Syringometaplasia is an adaptive, benign, metaplastic cellular process that affects the eccrine ducts and glands in response to a variety of physiological or pathological stimuli. Different subtypes of syringometaplasia have been described, including the squamous, mucinous, and adenomatous types. These metaplastic changes have been reported in association with chemotherapeutic agents, as well as with a variety of skin disorders including multiple infectious, neoplastic, and inflammatory skin diseases. In this review, we attempt to shed light on the different patterns of syringometaplasia, its pathogenesis, the plethora of skin conditions in which it may be observed, and the differential diagnoses that should be considered.

Multiple urethral stones causing penile gangrene

Penile urethral stones are a rare occurrence resulting from a number of causes including migration of stones within the urinary tract, urethral strictures, meatal stenosis, and obstructing tumours such as adenomatous metaplasia of the uroepithelium, hypospadias, urethral diverticulum, and very rarely primary fossa navicularis calculi. We report the case of a 54-year-old male presenting with penile gangrene and sepsis resulting from impaction of multiple stones within the penile urethra. This paper summarises the topic and discusses the pathophysiology of this unusual condition.

Nephrogenic adenoma of the urinary tract: clinical, histological, and immunohistochemical characteristics

Nephrogenic adenoma is a benign condition of the urinary tract resulting from the displacement and seeding of renal tubular cells from the renal pelvis to the urethra. A retrospective series of 134 cases collected from four hospitals in three different countries was analyzed in this study. Recorded clinical data included age and sex, topography, urological antecedents, coexistent lesions, and follow-up. Cytonuclear and architectural features were reviewed, and PAX-8, p63, PSMA, S100A1, CEA, EMA, CD117, cannabinoid receptor CB1, AMACR, E-cadherin, and CD10 antibodies were included in an immunohistochemical panel. Males predominated (105 M/29 F) with an average age of 66 years (range, 14-96). Urothelial carcinoma was the most frequent clinical antecedent (43.2 %) and also the most common coexisting lesion (14 %). Tubular architecture was the most frequent pattern detected (40 %) although most cases showed a mixed pattern (45.5 %). Deep infiltrative growth into the muscularis propria occurred in two cases. EMA and PAX-8 were expressed in 100 % of nephrogenic adenomas, while E-cadherin reactivity was observed in 66.6 % of cases, cannabinoid receptor CB1 in 25 %, CD10 in 13.6 %, CD117 in 4.1 %, and AMACR in 2.7 %. For the rest of the antigens, no reactivity was found. The average time lapse between the pathological antecedent and the discovery of a nephrogenic adenoma was 32 months. We conclude that nephrogenic adenoma displays a broad spectrum of histological features that may mimic malignancy. In our experience, CB1 immunostaining adds a further argument in favor of a renal origin of this lesion. The combination of PAX-8+, p63-, and EMA + distinguishes nephrogenic adenoma from urothelial and prostate carcinoma, its most frequent malignant look-alikes.

Nephrogenic adenomas in pediatric patients: a morphologic and immunohistochemical study of 21 cases

Similar to nephrogenic adenomas in adults, those in children are rare benign lesions that often occur in the setting of previous surgery or chronic irritation of the urinary tract. These lesions often present with hematuria and/or as polypoid or papillary lesions on cystoscopy, which may indicate malignancy. We sought to evaluate the various patterns of nephrogenic adenoma occurring in the pediatric population and better characterize the immunophenotype of these lesions. We reviewed 21 cases of nephrogenic adenomas from urinary bladder biopsies of 16 patients. Most patients had a history of urinary bladder augmentation with recurrent urinary stones and urinary tract infections. Many cases presented as a papillary or polypoid mass on cystoscopy. The most common morphologic patterns are papillary, tubulocystic, and a mixed pattern of papillary and tubulocystic, followed by cystic and tubular. On immunostaining, PAX-2, PAX-8, CK7, and MUC-1 provided the most diffuse and intense positive reactivity for nephrogenic adenoma, whereas CD10 and P504S were focal and lesser in intensity when positive. p63 and PAX-5 were consistently negative. We conclude that, although rare in children, nephrogenic adenoma should be included in the differential diagnosis of papillary/polypoid lesions in the urinary tract, especially in the context of previous surgery, chronic irritation from recurrent urinary tract infections, or stones. The immunohistochemistry profile of nephrogenic adenomas in our study also provides evidence that these are derived from distal renal tubular cells. In difficult cases, an immunohistochemical panel consisting of cytokeratin 7, PAX-2, PAX-8, and MUC-1 may be useful.

Nephrogenic adenoma of the ureter

Nephrogenic adenoma (NA) is an uncommon benign lesion of the urothelial tract. The diagnostic features that are useful in the recognition of this benign entity are: the characteristic mixture of various architectural patterns, associated stromal edema and inflammation, hyaline sheath around tubules, and lack of mitotic activity. Although NA appears with hematuria or obstruction, frequently found incidentally in endoscopy or imaging modalities.

Nephrogenic Adenoma of the Urinary Tract

Nephrogenic adenoma (NA) is an uncommon and intriguing lesion in the urinary tract. The pathogenesis of NA is not entirely clear. NA was considered to be a metaplastic process of the urothelium in response to chronic irritation of the urinary tract. However, recent evidence has shown that NA is not a metaplastic lesion but rather a proliferation of exfoliated and implanted renal epithelial cells in the urinary tract. Histologically, NAs exhibit, singly or in combination, tubules, small papillae, and microcystic structures lined by cells with little cytological atypia and focal hobnail changes. Solid formations and compressed spindled cells within a fibromyxoid background are rarely observed. Differential diagnosis includes, but is not limited to, malignant neoplasms occurring at the same sites, in particular urothelial carcinoma with deceptively bland morphology (with small tubules, microcystic and nested variants), prostatic adenocarcinoma, and clear cell adenocarcinoma. Immunohistochemical studies with antibodies targeting members of the paired box gene family (PAX2 and/or PAX8) in NAs may be helpful in the differential diagnosis of urothelial lesions and prostatic adenocarcinoma. NAs are most likely to be confused with clear cell adenocarcinoma, especially in small biopsy specimens. This is confounded by both lesions being frequently positive for PAX2, PAX8, and CK7 and not infrequently positive for p504S (α-methylacyl-CoA-racemase, AMACR) by immunohistochemistry. Recognition of its characteristic morphological patterns and awareness of its unusual architectural and cytological features are important in making the diagnosis of NA and distinguishing this lesion from its mimickers.

S-100A1 is a reliable marker in distinguishing nephrogenic adenoma from prostatic adenocarcinoma

Nephrogenic adenoma is a benign lesion that may occur at any site of the genitourinary tract, usually in association with previous urothelial injuries. Although its pathogenesis is still debated, recent studies seem to confirm its derivation from renal tubular epithelium, rather than from a metaplastic process of urothelium. In addition to its uncertain origin, there can be diagnostic difficulty in distinguishing nephrogenic adenoma from prostatic adenocarcinoma, particularly with lesions arising in the prostatic urethra. So far, immunohistochemical stains are often needed to make such a distinction, and several markers have been proposed, often with controversial results. S100A1 is a calcium binding protein that has been recently reported to be expressed in renal tubular cells and in a subset of renal cell neoplasms. Alpha-methylacyl-CoA racemase (AMACR), a recently identified prostate cancer marker, has also been found to be expressed in renal tubules and in some renal epithelial neoplasms. In this study, we investigated the expression of S100A1 and AMACR in 18 nephrogenic adenomas and in 100 prostatic adenocarcinomas. A strong and distinct cytoplasmic or nucleocytoplasmic staining of S100A1 was found in 17 out of 18 cases of nephrogenic adenoma (94%), but never in prostatic adenocarcinoma. In contrast, AMACR expression was detected in 14 of 18 nephrogenic adenomas (78%) and in 96 of 100 prostatic adenocarcinomas (96%). We conclude that (1) S100A1 is a specific and sensitive immunohistochemical marker to differentiate nephrogenic adenoma from prostatic adenocarcinoma; (2) AMACR immunostaining does not seem to be a useful marker in distinguishing between these 2 lesions; (3) given that both S100A1 and AMACR have been reported to be expressed in renal tubular cells and in a subset of renal cell neoplasms, our findings confirm the histogenetic relationship between nephrogenic adenoma and renal tubular epithelium.

Nephrogenic adenoma of the ureter: case report

Nephrogenic adenoma is a rare metaplastic benign lesion of urothelium in response to genitourinary tract procedures, chronic infection, trauma, urinary calculi and immunosuppressive therapy after renal transplantation. It has been reported to occur throughout the urinary tract especially, in the urinary bladder. We report a case of nephrogenic adenoma arising from the lower end of the right ureter with clinical and radiological features suspicious of carcinoma.

Nephrogenic adenoma: an update on an innocuous but troublesome entity

Nephrogenic adenoma (NA) is a rare benign lesion of the urothelial tract that is typically preceded by some form of genitourinary insult. The pathogenesis of NA is not entirely clear. Although generally presumed to be a metaplastic process of the urothelium, recent evidence suggests that NA may in fact be derived from detached renal tubular cells implanting along the urothelial tract in previously injured areas, at least in cases associated with a kidney transplant. On light microscopy, NA shows a variety of patterns, including tubulocystic, papillary, and much less frequently solid, that often coexist. Recognition of its characteristic patterns, and awareness of its unusual architectural and cytologic features, is key to making the diagnosis of NA and distinguishing this lesion from malignant neoplasms occurring at the same sites, in particular, clear cell carcinoma, nested or microcystic variants of urothelial carcinoma and prostatic adenocarcinoma. Although straightforward in most cases, the correct diagnosis may be difficult to make on limited tissue samples. A number of immunohistochemical markers have been studied in an attempt to characterize NA; however, to date there is no specific immunohistochemical profile to distinguish this lesion from its malignant mimickers, although PAX2, a new marker, may prove to be helpful in this regard. Clinicopathologic correlation with careful attention to morphology remains the pillar in establishing the correct diagnosis.

Nephrogenic Adenoma: Immunohistochemical Evaluation for Its Etiology and Differentiation From Prostatic Adenocarcinoma

Context.—Nephrogenic adenoma is a rare benign lesion of the urinary tract. Owing to its strong association with a history of urinary tract irritation, nephrogenic adenoma was initially thought to originate from urothelial metaplasia; however, no solid proof of this association has been found. More recent investigation has pointed to a renal tubular cause. In addition to its uncertain origin, there can be diagnostic difficulty in distinguishing nephrogenic adenoma from prostatic carcinoma, particularly when dealing with lesions from the prostatic urethra.

Objective.—To elucidate a possible histogenic relationship between nephrogenic adenoma and renal tubules, and also to evaluate the role of immunohistochemistry in the diagnostic distinction between nephrogenic adenoma and prostate carcinoma.

Design.—Immunohistochemical studies were performed for P504S, prostate-specific antigen, CD10, p63, and epithelial membrane antigen on 9 cases of nephrogenic adenoma, 10 cases of normal renal parenchyma, and 10 cases of prostatic tissue, both benign and malignant.

Results.—Nephrogenic adenoma shares the same immunohistochemical profile as distal renal tubules: both are positive for P504S and epithelial membrane antigen and negative for p63, CD10, and prostate-specific antigen. Prostatic adenocarcinoma tissue was positive for P504S and prostate-specific antigen, and normal prostatic gland tissue was positive for prostate-specific antigen and negative for P504S; p63-stained basal cells in normal prostatic gland tissue but did not react with prostatic adenocarcinoma tissue. The CD10 inconsistently stained normal and neoplastic prostatic gland tissue. Epithelial membrane antigen stain was negative in prostatic carcinoma, with rare occasional reactivity in normal prostatic glands.

Conclusion.—These findings provide supporting evidence that nephrogenic adenoma is derived from distal renal tubules. Our results also demonstrated that the combination of P504S and prostate-specific antigen with epithelial membrane antigen is a valuable tool in distinguishing prostatic carcinoma from nephrogenic adenoma.

Mesonephroid adenocarcinoma arising from mesonephroid metaplasia of the urinary bladder

We present a rare case of mesonephroid adenocarcinoma arising from mesonephroid metaplasia of the urinary bladder. For the first time, the unique histopathologic features in this patient provide evidence for the theory that vesical mesonephroid adenocarcinoma might be a highly aggressive metaplastic variant of urothelial carcinoma that should be treated accordingly.

PAX2: a reliable marker for nephrogenic adenoma

Nephrogenic adenoma is a rare lesion of the urinary tract. The diagnosis usually is straightforward when characteristic microscopic and clinical findings are present, and the entity is familiar. However, misdiagnosis, in particular of adenocarcinoma of the prostate gland, may occur. Immunohistochemical stains often are needed to make such a distinction, but currently available markers offered only partial help. It recently was demonstrated that nephrogenic adenoma in renal transplant patients originated from the renal tubular epithelium. This newly proved, but long sought information may be helpful in the differential diagnosis of nephrogenic adenoma. In this study, we investigated the expression of a renal transcription factor, PAX2, in 39 nonrenal transplant-related nephrogenic adenomas, 100 adenocarcinomas of the prostate gland, and 47 urothelial carcinomas of the urinary tract. A strong and distinct nuclear staining of PAX2 was found in all 39 cases of nephrogenic adenoma (100%), but not in normal prostate tissue, normal urothelium, adenocarcinomas of the prostate gland, and invasive urothelial carcinomas. Focal CD10 was detected in six of 13 nephrogenic adenomas in the superficial papillary component and in normal prostate epithelium, normal urothelium, lymphocytes, adenocarcinoma of the prostate gland, and urothelial carcinoma. There was no uroplakins detected in nephrogenic adenoma. Therefore, these findings are suggesting that nephrogenic adenoma in nonrenal transplant patients may also arise from the renal epithelium, as did the comparable lesions after transplantation. PAX2 is a specific and sensitive immunohistochemical marker in identification and differential diagnosis of nephrogenic adenoma.

Renal-type clear cell carcinoma occurring in the prostate

Clear cell lesions of the urinary tract often present diagnostic challenges. We report a previously undescribed lesion in the prostate, occurring in a 73-year-old man who presented with hematuria and subsequently underwent transurethral resection of the prostate. A total of 24 g of tissue was removed, and in 4 of 17 blocks submitted a lesion morphologically and immunohistochemically similar to clear cell carcinoma of the kidney was noted. A thorough cystoscopic and full-body, radiologic workup was performed, but no renal tumor was discovered. Random cystoscopic biopsies of the bladder and prostatic urethra as well as bladder washings were benign. Subsequent needle biopsies of the prostate were also benign. The patient underwent a pelvic lymph node dissection with radical cystoprostatectomy and orthotopic Studer pouch diversion. There was organ-confined, ordinary-type prostatic adenocarcinoma (Gleason's 3 + 3) present bilaterally in the peripheral zone; no residual clear cell carcinoma was identified. All lymph nodes were negative, and the urinary bladder showed no dysplasia or neoplasia. We think this tumor represents a primary renal type of clear cell carcinoma arising in the prostate. To our knowledge, this type of tumor has not been previously reported to arise in an extrarenal location.

Nephrogenic adenoma of the prostatic urethra in a patient treated with ESWL for a lower ureteral stone

We present a case of prostatic urethral nephrogenic adenoma incidentally diagnosed in a patient treated with ESWL for ureteral stone disease, and we comment on this unusual urothelial lesion.

Derivation of nephrogenic adenomas from renal tubular cells in kidney-transplant recipients

BACKGROUND

Nephrogenic adenomas are benign, tumor-like lesions within the urothelial mucosa of the urinary tract that are not uncommon in renal-transplant recipients. We investigated the origin of nephrogenic adenomas in renal-transplant recipients.

METHODS

Tissue sections were analyzed by fluorescence in situ hybridization with the use of probes for the X and Y chromosomes, by immunohistochemical methods with the use of antibodies to renal tubular antigens, and by lectin histochemical methods. Forty-six nephrogenic adenomas from 29 patients were analyzed.

RESULTS

All nephrogenic adenomas in 14 female recipients of transplants from male donors and 10 male recipients of transplants from female donors showed the same sex-chromosome status as the donor kidney, but not the same sex-chromosome status as the recipient's surrounding bladder tissue. The nephrogenic adenomas from all 6 female recipients of transplants from female donors showed female chromosomes, and those from the 16 male recipients of transplants from male donors showed male chromosomes. The presence of aquaporin 1, PAX2, and lectin-binding capacity for peanut agglutinin, Lotus tetragonolobus agglutinin, and Sophora japonica agglutinin in nephrogenic adenomas indicated an origin from renal tubular cells.

CONCLUSIONS

Nephrogenic adenomas in renal-transplant recipients are derived from tubular cells of the renal transplants and are not metaplastic proliferations of the recipient's bladder urothelium.

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.

Nephrogenic adenoma of the prostatic urethra: a mimicker of prostate adenocarcinoma

Nephrogenic adenoma, thought to be a benign metaplastic response of the urothelium to injury, can rarely affect the prostatic urethra. Extension of small tubules of nephrogenic adenoma into the underlying prostatic fibromuscular stroma can lead to the misdiagnosis of prostatic adenocarcinoma in transurethral resection specimens and prostate biopsies. We reviewed 26 cases of nephrogenic adenoma involving the prostatic urethra, seen at The Johns Hopkins Hospital from 1990 to 1998, to evaluate the histologic features, which may better define this lesion. Immunohistochemical results were evaluated for cases where the lesion was present on deeper sections. Histologic patterns included the following: tubules in 96% (25 of 26), structures resembling vessels in 73% (19 of 26), cords and individual cells in 46% (12 of 26), papillary configurations in 19% (5 of 26), and signet ring cell-like tubules in 12% (3 of 26). Other features of nephrogenic adenoma, such as thyroidization, were identified in 38% (10 of 26), and peritubular sheaths were seen in 65% (17 of 26) of cases. Nucleoli were prominent in 54% (14 of 26), and no case had mitoses. In the region of nephrogenic adenoma, urothelium was noted in 69% (18 of 26); in 61% (11 of 18) it showed cuboidal metaplasia and 28% (5 of 18) showed squamous metaplasia. Extension of nephrogenic adenoma into muscle was observed in 77% (20 of 26) of cases, 75% (15 of 20) of which had identifiable urothelium overlying the lesion. Blue-tinged mucinous secretions were observed in 32% (8 of 25) of cases. Inflammation was found in all but one case. Nephrogenic adenomas were diffusely positive for 34betaE12 in 11% (1 of 9) of cases, focally positive in 44% (4 of 9), and negative in 44% (4 of 9). In 100% (9 of 9), cytokeratin 7 stains were positive. Focal prostate specific antigen and PSAP positivity were seen in 36% (4 of 11) and 50% (5 of 10) of nephrogenic adenoma cases, respectively. In conclusion, nephrogenic adenoma of the prostatic urethra can mimic prostate cancer because of: 1) the presence of tubules, cords, and signet ring-like tubules; 2) prominent nucleoli; 3) muscle involvement; 4) blue-tinged mucinous secretions; 5) focal prostate specific antigen and PSAP positivity; and 6) negative staining in some cases for 34betaE12. Features useful in the diagnosis of nephrogenic adenoma include the following: 1) distinctive nephrogenic patterns, such as papillary and "vascular," 2) adjacent urothelium, 3) thyroidization, 4) peritubular sheaths, 5) associated inflammation, and 6) positivity for cytokeratin 7 and, in some cases, 34betaE12.

Urinary bladder. Mimics of neoplasia and new pathologic entities

A wide range of epithelial and mesenchymal pseudoneoplastic disorders of the urinary bladder may clinically and pathologically mimic a malignant neoplasm. These lesions usually require a tissue biopsy for definitive diagnosis. It is important to be aware of these lesions and their spectrum of morphologic appearances to avoid overdiagnosis and inappropriate aggressive therapy.

Nephrogenic adenoma of the bladder in renal transplant and non-renal transplant patients: a review of 22 cases

OBJECTIVES

To review diagnoses of nephrogenic adenoma and in particular to evaluate its association with transitional cell carcinoma (TCC) of the bladder and its relationship to renal transplantation.

METHODS

A retrospective review of 22 cases of nephrogenic adenoma (NA) diagnosed between 1989 and 1996 was conducted, 7 of which were in renal transplant patients. Data collected in each case included demographic details, predisposing factors, associated urologic pathology, mode of presentation, cystoscopic finding, management, and follow-up.

RESULTS

There was a 3:1 predominance of men. Mean follow-up was 21.4 months (range 3 to 50). Six patients (27%) had one or more recurrences. All 22 patients had some form of previous bladder insult or surgery, including recurrent urine infections, urinary tract instrumentation, placement of ureteric stents, cystodiathermy, and open bladder surgery. Six cases were associated with TCC of the bladder, of which 4 had NA lesions directly over or close to the site of previous fulguration. In 4 patients, there was a temporal relationship between the administration of intravesical doxorubicin hydrochloride or bacille Calmette-Guérin (BCG) and the onset of NA lesions. One case was associated with an inverted papilloma that had not been described before. In 7 renal transplant cases, 3 lesions were found contralateral to the side of the ureterovesical anastomosis. All 22 cases were benign histologically, but one NA was found within a low-grade baldder TCC. Nineteen cases were followed up regularly with no malignant transformation. Three patients were lost to follow-up.

CONCLUSIONS

This study has demonstrated an association between NA and bladder cancer. Patients with NA, especially those treated with intravesical chemotherapy or BCG, should have regular cystoscopies. Fulguration or transurethral resection appear to be sufficient treatment. No renal transplant patients had vesical TCC and NA simultaneously. Neither immunosuppression nor ureterovesical anastomosis appeared to be a significant predisposing factor in the transplant patients.

Nephrogenic adenoma after urethral reconstruction using bladder mucosa: report of 6 cases and review of the literature

PURPOSE

To our knowledge nephrogenic adenoma, an unusual benign metaplastic lesion of the urothelium, has not been reported previously following urethral reconstruction using bladder mucosa. Histopathological features, etiological factors and clinical features are discussed.

MATERIALS AND METHODS

We reviewed the records of 117 patients who underwent hypospadias repair with free grafts of bladder mucosa from 1982 to 1995.

RESULTS

Five children 6 to 11 years old and a 39-year-old man had nephrogenic adenoma of the urethra. Hematuria or dysuria was the usual reason for presentation. The lesions were located at the site of anastomosis between the graft and proximal urethra in 3 cases and the distal graft in 2, and they involved the whole graft in 1. Successful treatment consisted of endoscopic resection of the polyps in 4 patients, while open surgical correction was performed in 2, requiring complete excision of the previous graft in 1 and segmental resection in 1.

CONCLUSIONS

The gross appearance of the lesion may be confused with that of transitional cell carcinoma or clear cell adenocarcinoma of the urethra, necessitating biopsy to rule out malignancy. Endoscopic management is possible for small tumors, although severe nephrogenic adenoma involving most of the reconstructed urethra may require complete resection of the graft and creation of a new urethra.

Nephrogenic adenoma of the bladder in renal transplant recipients: a report of 9 cases with assessment of deoxyribonucleic acid ploidy and long-term followup

PURPOSE

We evaluated the outcome of nephrogenic adenoma, a benign tumor rarely encountered in renal transplant recipients.

MATERIALS AND METHODS

Between 1985 and 1993, 9 renal transplant recipients with a nephrogenic bladder adenoma removed by endoscopic resection were followed for 24 to 88 months (mean 40). Tumor deoxyribonucleic acid ploidy was assessed by flow cytometry at diagnosis and/or relapse.

RESULTS

The relapse rate was 88%. The tumors were diploid and of low proliferating potential, and showed no malignant transformation.

CONCLUSIONS

Our study confirms the lack of premalignant potential of nephrogenic adenomas. However, since transplant recipients might be at increased risk for bladder cancer, they should be followed closely.

L'adenoma nefrogenico della vescica. Caso clinico

The Authors report a case of nephrogenic adenoma of the bladder in an 8-year-old girl. The diagnostic and therapeutic management are described and the various histogenetic theories are discussed.

Vesical clear cell adenocarcinoma. V. Nephrogenic adenoma: a diagnostic problem

Following the diagnosis of nephrogenic adenoma in a bladder lesion, which was later interpreted as early clear cell adenocarcinoma, the morphological and immunocytochemical features of these two lesions were reviewed to see if differences could be established for future diagnostic application. The architecture, extent, cell type, nuclear pleomorphism, presence of mitotic figures and glycogen content were recorded in 28 nephrogenic adenomas and the clear cell carcinoma. Similarly, the immunoreactivity for CAM 5.2, LP34, EMA and CEA of 10 nephrogenic adenomas and the clear cell carcinoma were compared. Proliferation rate in five nephrogenic adenomas and the carcinoma was assessed by antibody M1B1. Many of the features showed differences in degree or extent (clear cell change, nuclear pleomorphism, CAM 5.2 and CEA positivity). The only features distinct to clear cell carcinoma were the presence of solid islands, mitoses greater than 1/10 HPF (HPF area = 0.4 mm2) and M1B1 counts in excess of 29/200 in clear cell carcinoma (range 30/200-83/200). Only the high M1B1 count was present in the first biopsy of the clear cell carcinoma.

Nephrogenic adenoma in a bladder diverticulum

Nephrogenic adenoma is a rare proliferative response of urothelium to chronic irritation or infection. It has been reported to occur in various locations in the urinary tract, including the renal pelvis, ureter, bladder and urethra, and within an ileal conduit. We report our experience with this lesion occurring in a bladder diverticulum.

Bladder tumours in Chinese: a 6 year study

Specimens from 334 Chinese patients who underwent surgical treatment for bladder tumours over a 6 year period were studied retrospectively. Transitional cell carcinoma (TCC) accounted for 91.3% of all the bladder tumours. The male to female ratio was 3:1 and the mean age was 69 years. Papillary TCC, which represented 67.5% of all TCC, were more often of a lower grade compared to non-papillary tumours. The staging of tumours was done for the 102 cystectomy specimens with TCC only. Among these, 28% were superficial while 72% were muscle-invasive and the papillary TCC usually presented at an earlier stage. Infiltration into the prostate gland was identified in 11% of male patients while coexisting adenocarcinoma of the prostate was observed in another 4.2%. Other types of carcinoma were uncommon. Squamous cell carcinoma, adenocarcinoma and small cell carcinoma accounted for 2.7, 1.8 and 0.6% of all bladder tumours, respectively. A rare case of sarcomatoid carcinoma was also found, but no true sarcoma was documented in this series. Benign lesions included five inverted papillomas, three nephrogenic adenomas, two paragangliomas and one haemangioma.

Tubulo-papillary adenoma (so-called nephrogenic adenoma) arising in the renal pelvis. Report of a case with a critical consideration of histogenesis and terminology

This is the first detailed clinical and histopathologic report of a tubulo-papillary adenoma (so-called nephrogenic adenoma) arising in the renal pelvis of a 35-year-old woman. The tumor showed a polypoid exophytic growth and consisted of closely packed tubular formations lined by cuboidal to low columnar cells with an admixture of delicate papillary structures. Its benign nature was indicated by the lack of cellular atypias, the extremely low proliferative activity and the absence of invasiveness. We favor the metaplastic theory of origin rather than an embryologic (dysontogenetic) derivation from mesonephric remnants as the underlying histogenetic principle. The descriptive term "tubulo-papillary adenoma" seems more appropriate than the designation "nephrogenic adenoma". True tumors of this type should clearly be distinguished from metaplastic tubular, papillary or tubulo-papillary cuboidal hyperplasias of the urothelium (so-called nephrogenic metaplasia) which are considered preneoplastic and assumed to be immediate precursors of adenomas of the lower urinary tract.

Nephrogenic adenoma of the bladder: urographic spectrum

Nephrogenic adenoma is a rare, proliferative response of urothelium to urinary infection or injury of the bladder mucosa. Histologically, the lesion resembles proximal tubules of the nephron. While it can occur throughout the urinary tract, it usually appears in the bladder, with diverse radiographic manifestations. Of 6 patients with nephrogenic adenoma of the bladder, 3 presented with masses in the bladder and 2 with irregularities of the bladder mucosa on urography, while 1 showed no focal urographic abnormalities. There were no distinctive radiographic features of nephrogenic adenoma that would allow it to be differentiated from tumor or other inflammatory lesions. Although it is considered benign, bladder involvement may be extensive and eradication of the tumor may be difficult.

Nephrogenic adenoma. Reports of two cases

Nephrogenic adenoma is a rare lesion of the urinary tract. Two cases in the urinary bladder are described. Histologically the tumor consists of cystic and tubular structures resembling the distal part of the nephron. The etiology and pathogenesis are discussed and a new etiologic theory is presented.