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Nephrogenic adenoma is a rare and benign tumour of the urinary tract thought to be caused by metaplastic change of native urothelial tissue. The majority of cases arise in the bladder, with very few cases affecting the ureter reported in the literature. Herein, we describe the presentation, diagnostic challenges, and the eventual management of a nephrogenic adenoma of the ureter by robot-assisted laparoscopic nephroureterectomy. Urologists and pathologists should be aware of the potential diagnostic and management pitfalls associated with this rare tumour, as well as the sparsity of evidence with respect to follow-up.

Management of malignant urothelial tumors is often associated with extended costly treatments, some with significant morbidity. Advanced tumors are treated with radical cystectomy with neoadjuvant or adjuvant radiation or chemotherapy. Over and under interpretation of histological findings from biopsies and transurethral resections of urothelial lesions may either incur treatments with significant side effects or miss a possible window of cure, respectively. Herein we reflect our approaches and common diagnostic challenges of urothelial tumors and their mimickers, and highlight the diagnostic pitfalls and key histological and immunohistochemical differentiating features. It is useful to separate mimickers of bladder adenocarcinoma and mimics of urothelial carcinoma as the former can involve the muscularis propria, whereas the latter do not. Glandular mimickers discussed herein include cystitis cystica et glandularis with intestinal (colonic) metaplasia, endocervicosis and endometriosis, and nephrogenic adenoma. Common mimickers of urothelial carcinoma include polypoid cystitis, pseudocarcinomatous urothelial neoplasia, inverted urothelial papilloma, florid proliferation of von Brunn nests, and reactive urothelial metaplasia associated with prostatic infarction. We emphasize where clinical impression and history are important for the correct diagnosis. In some entities assessment of the entire histological picture is critical rather than focusing on isolated findings that out of context may be indistinguishable from cancer.

Summary Antibodies targeting uroplakin II (UPII) are highly specific for urothelial cells and are frequently used to determine if a primary bladder lesion or a metastatic lesion originates from the urothelium. However, to date, no studies have tested the expression of UPII in histological mimickers of bladder cancer that are nonurothelial in origin. Given the potential risk of misdiagnosis, immunohistochemical markers are often used to better characterize these lesions. In the present study, we analyzed the immunohistochemical expression of UPII in a set of urothelial carcinoma mimickers that included conventional nephrogenic adenoma (n = 8), papillary nephrogenic adenoma (n = 6), endometriosis/endosalpingiosis (n = 5), inflammatory myofibroblastic tumor (n = 4), ectopic prostate tissue (n = 2), and malakoplakia (n = 2). We also examined the expression of GATA-3, another commonly used immunohistochemical marker in bladder cancer diagnosis, in the same lesions. Weak immunoreactivity for UPII was identified in 6 of 27 mimickers (22%), and GATA-3 was expressed in 16 of 27 mimickers (59%). Strong immunoreactivity for UPII appeared to be a specific marker for urothelial cell of origin, although weak staining was seen in a significant proportion of mimickers. GATA-3 immunostaining was present in a greater number and broader spectrum of mimickers; however, only one case of papillary nephrogenic adenoma showed dual positivity for UPII and GATA-3. These findings support the immunohistochemical panel-based approach in the diagnosis of bladder lesions, especially if nonurothelial bladder cancer mimickers are in the differential diagnosis. Additional larger studies would be of value to expand on these findings.

Attention of the pathologist to basic urinary bladder anatomy and histology is essential to accurately diagnose bladder pathology, as well as determine TNM staging for proper prognostic evaluation. In this chapter, the normal anatomy, histology, and benign pathology of the urinary bladder are reviewed, with emphasis on key points that the surgical pathologist should know. Topics covered herein include bladder cancer staging according to the most recent AJCC Staging Manual, differentiating muscularis propria from hypertrophic muscularis mucosa, gross evaluation and handling of bladder tumors, functional anatomy, urachal remnants, diverticula, exstrophy, ectopic prostate tissue, intestinal and squamous metaplasia, von Brunn nests/cystitis cystica and glandularis, nephrogenic adenoma, polypoid cystitis, types of inflammatory cystitis, malakoplakia, fibroepithelial polyp, and Mullerian lesions. Potential mimickers of malignancy are noted, and characteristics used to differentiate mimickers from malignant lesions are discussed. This chapter is therefore a useful reading for genitourinary pathologists, general surgical pathologists who encounter bladder cases, and pathology trainees.

Diagnosis and classification of urothelial carcinoma are usually straightforward based on gross and routine microscopic examination. However, immunohistochemistry can be very helpful in several situations. In this chapter we will discuss the general consideration and value of immunohistochemistry in some special diagnosis scenarios including distinction of urothelial reactive atypia from flat urothelial carcinoma in situ, assessment of the depth of invasion, establishment of urothelial lineage including differentiating urothelial carcinoma from secondarily tumor involving the bladder, differential diagnosis of spindle cell lesions, and therapeutic and prognosis prediction. Commonly used immunohistochemistry markers, panel’s selection, and immunohistochemistry profiles in the differential diagnosis of major urinary bladder lesions will be provided.

A broad spectrum of lesions, including hyperplastic, metaplastic, inflammatory, infectious, and reactive, may mimic cancer all along the urinary tract. This narrative collects most of them from a clinical and pathologic perspective, offering urologists and general pathologists their most salient definitory features. Together with classical, well-known, entities such as urothelial papillomas (conventional (UP) and inverted (IUP)), nephrogenic adenoma (NA), polypoid cystitis (PC), fibroepithelial polyp (FP), prostatic-type polyp (PP), verumontanum cyst (VC), xanthogranulomatous inflammation (XI), reactive changes secondary to BCG instillations (BCGitis), schistosomiasis (SC), keratinizing desquamative squamous metaplasia (KSM), post-radiation changes (PRC), vaginal-type metaplasia (VM), endocervicosis (EC)/endometriosis (EM) (müllerianosis), malakoplakia (MK), florid von Brunn nest proliferation (VB), cystitis/ureteritis cystica (CC), and glandularis (CG), among others, still other cellular proliferations with concerning histological features and poorly understood etiopathogenesis like IgG4-related disease (IGG4), PEComa (PEC), and pseudosarcomatous myofibroblastic proliferations (post-operative spindle cell nodule (POS), inflammatory myofibroblastic tumor (IMT)), are reviewed. Some of these diagnoses are problematic for urologists, other for pathologists, and still others for both. Interestingly, the right identification of their definitory features will allow their correct diagnoses, thus, avoiding overtreatment. The literature selected for this review also focuses on the immunohistochemical and/or molecular data useful to delineate prognosis. Sin financiación No data 2021 UEM

Introduction & Objectives Nephrogenic adenoma is a rare benign metaplastic lesion of the urothelium. The objective of this video is to describe the surgical technique in the case of a patient with persistent hematuria, presence of 25 mm filling defect in the pelvis and inferior calyceal region and histological result of nephrogenic adenoma after percutaneous resection, an exceptional location Materials & Methods 30-year-old woman consulted for persistent hematuria. Urinary cystoscopy and cytology were negative. Urography CT scan showed a 25 mm filling defect in the right renal pelvis. After retrograde flexible ureteroscopy observing sessile tumor, percutaneous surgery is considered, because during flexible ureteroscopy the visualization and approach were not safe and good. The patient was placed in a modified Valdivia position. Ascending pyelography was performed observing pyelocaliceal filling defect of 25 mm. Needle puncture guided by x-ray and ultrasound, flexible guide step and expansion with metal dilators with Amplatz sheath passage 16.5/17.5 fr. We started with minipercutaneous tract due to the localization of lesion (pyelocaliceal) and to decrease the chance of bleeding during initial access. Access with nephroscope, biopsy and vaporization with holmium laser. Due to the size of the lesion, Amplatz sheath was removed and dilatation with high pressure balloon was completed up to 30 fr caliber. A resectoscope with bipolar energy was introduced and the lesion was resected to the tumor base. A nephrostomy tube and simple ureteral catheter were placed. Results Twenty-four hours after surgery, a nephrostomy catheter was removed. Forty-eight hours after surgery, the bladder catheter and ureteral catheter were removed and the patient was discharged. The histological result confirmed the diagnosis of the initial biopsy: Nephrogenic adenoma. Six months after surgery, the patient is asymptomatic, and with normal CT Urography, without appreciating the defect of filling prior to surgery. Conclusions Although holmium laser is the standard treatment, percutaneous treatment of symptomatic benign tumors of the upper urinary tract with bipolar energy is a viable choice, since it allows the preservation of the renal unit, with minimal morbidity and excellent results.

Nephrogenic adenoma is a rare, benign lesion that can be encountered anywhere along the urinary tract. It is associated with genitourinary trauma, chronic inflammation, genitourinary surgery, renal transplant, urolithiasis, and radiation. In children, these lesions are almost exclusively found in the bladder. However, we report an unusual case of a 15-year-old boy with no prior urologic history who presented with an obstructing right ureteral nephrogenic adenoma that required an ileal ureter interposition and right ureterectomy.

Nephrogenic adenoma is a rare lesion that consists of epithelial cells arranged in tubular form, resembling tubules in the renal medulla, and is found usually in the urinary bladder although it can occur anywhere in the transitional epithelium of the lower urinary tract. The first case of nephrogenic adenoma of the urinary bladder was reported before the first kidney transplantation, and the lesion has been reported in patients with and without renal transplantation. The origin of cells in nephrogenic adenoma is debated and has been postulated to arise from cells of embryonic origin or from metaplasia secondary to chronic irritation or from implantation of allograft cells in patients with kidney transplantation. The long-term outcome and potential to convert into malignancy are not established, and therefore, there are no recommendations on how to follow up these patients. We present a case of a patient who was found to have nephrogenic adenoma of the urinary bladder during his second kidney transplantation from a cadaveric donor. He had undergone living donor kidney transplantation previously which subsequently failed. The patient did not manifest any symptoms of nephrogenic adenoma. During a follow-up period of 5 years, he has not manifested any symptoms related to nephrogenic metaplasia. Histopathological examination 5 years after the second transplantation did not show any malignant change. It can be concluded that nephrogenic adenoma is likely to behave in benign fashion post kidney transplantation.

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.

RATIONALE Nephrogenic adenoma (NA) is a rare benign lesion of the urinary tract, which rarely occurs in the renal pelvis. Only 19 cases have been reported in the literature. However, there is no detailed report on the clinicopathological features of NA of the renal pelvis. PATIENT CONCERNS This case report describes a 46-year-old male patient who was admitted to the hospital for one month because of painless gross hematuria with blood clots. He had a history of hyperuricemia and a family history of gastric cancer. DIAGNOSES NA of the renal pelvis was diagnosed pathologically and immunohistochemical. INTERVENTIONS The patient underwent laparoscopic nephroureterectomy. OUTCOMES The patient recovered well after the operation with no discomfort. In addition, we followed up with the patient regularly post-discharge (approximately 20 months). There were no obvious abnormalities in the results of routine urine culture, computed tomography scan of the abdomen, and cystoscopy during the follow-up period, and the symptoms disappeared completely and did not recur. LESSONS NA of the renal pelvis is extremely rare in the clinic, which can be easily misdiagnosed and overtreated. However, for pathological diagnosis of this disease, specific immunohistochemical staining for preoperative biopsy was reported to be significant, which should be considered by the urologists and pathologists.

Background: Bladder cancer is relatively common in adults. In children, it is extremely rare and in the majority of cases, low grade, low stage urothelial cancers are found. Case report: We describe the diagnostic, therapeutic, and follow-up management of bladder cancer in a 3-year-old boy examined for painless hematuria. Transurethral resection of the tumor was performed and T1 high grade urothelial cancer with osseous metaplasia was found in definitive specimens. During the 2-year follow-up, there has been no recurrence. Typical characteristics of the most prevalent bladder tumors are presented. Conclusion: Despite its low incidence and low prevalence bladder cancer in children is a very serious condition which must not be missed in the differential diagnosis of hematuria or urinary tract infection. It is vital to differentiate urothelial cancer from hamartoma and nephrogenic adenoma and, particularly in osseous metaplasia, from sarcomatoid carcinoma. Especially in high-grade cancers, precise TUR of the tumor with a careful follow-up is essential to detect cancer recurrence and reduce progression.

Background: Nephrogenic adenoma is a benign lesion found in the genitourinary tract, often at sites of prior inflammation, and is characterized by tubular, papillary, or tubulopapillary structures. It is thought to arise from distal migration and implantation of renal tubular cells into the renal pelvis, ureter, bladder, or urethra. These tumors often resemble malignant neoplasms. Morphologic variants include small tubules, signet ring-like pattern, papillary formations, flat pattern, and vessel-like structures. A fibromyxoid variant was first described in 2007. Here, we present the first known cases of fibromyxoid nephrogenic adenoma of the ureter. Case Presentations: A 79-year-old white man presented with asymptomatic right hydroureteronephrosis to the level of the mid-ureter with associated right ureteral wall thickening found on surveillance CT scan for lymphoma. A 59-year-old white man presented with a right ureteral stricture after ureteroscopic ureteral injury and underwent effective robotic ureteroureterostomy. Pathology analysis in both cases revealed fibromyxoid nephrogenic adenoma. Conclusion: Fibromyxoid nephrogenic adenoma may occur in the ureter. Knowledge of this rare tumor is important for urologists and pathologists to prevent misdiagnosis and overtreatment of a typically benign process.

BACKGROUND Severe labial agglutination can be refractory to outpatient management and can lead to voiding dysfunction in postmenopausal women. Labial agglutination is often a sequela of long-standing inflammatory processes, which include untreated lichen planus, lichen sclerosus, and atrophic vaginitis. CASE An 82-year-old parous woman presented with severe labial agglutination and complete obstruction of her vaginal introitus, causing obstructive voiding symptoms. She underwent a surgical procedure to release the fused labia. Pathologic evaluation of a vulvar biopsy revealed nephrogenic adenoma, which is an uncommon benign lesion usually presenting in the urinary tract. CONCLUSIONS Refractory, severe labial agglutination in postmenopausal women can lead to significant voiding dysfunction, and the underlying chronic inflammation may result in pathologic changes such as nephrogenic adenoma. Pathologic tissue diagnosis is important to plan appropriate surveillance for patients with this chronic condition.

Urethral cancer is a rare malignancy with urothelial subtype being the most common followed by adenocarcinoma. In women, the usual presentation is urinary retention and hematuria. Clear cell variety of adenocarcinoma is a rarer entity which usually has a better prognosis than other variants. Lymph node metastasis is seen in about 30% of urethral cancers. Histopathological differential diagnosis includes Skene gland carcinoma and nephrogenic adenoma. Herein, we present a 58-year-old female patient who presented for evaluation of lymph node mass in the inguinal region. The detailed evaluation revealed clear cell adenocarcinoma of the urethra as the primary with lymph node metastasis.

Nested variant of urothelial carcinoma is a rare variant of urothelial carcinoma morphologically characterized by infiltrative nests of cytologically bland urothelial cells. It is widely recognized that nested variant of urothelial carcinoma can closely mimic von Brunn nests. However, nested variant of urothelial carcinoma with tubule formation can also resemble nephrogenic adenoma, where immunohistochemical positivity for PAX8 has been used to establish the diagnosis of nephrogenic adenoma. Following anecdotal examples of PAX8 positive nested variant of urothelial carcinoma, we formally evaluated 23 cases of nested variant of urothelial carcinoma from 2011 to 2018. Cases were collected from our institution and evaluated for their architectural pattern and PAX8 expression. Except for 1 case from the renal pelvis, cases were located in the bladder. The majority (14/23 [61%]) showed solid nests with at least focal tubular differentiation. PAX8 immunoreactivity was strong (3+) in 7 (30%), moderate (2+) in 6 (26%), and negative in 10 (44%) cases. Four (57%) of the cases with strong expression and 3 (50%) of those with moderate staining showed diffuse immunoreactivity. Moderate-strong immunoreactivity was seen in 4/6 (66.7%) cases with solid nests, 8/14 (57.1%) with solid nests and tubules, and 1/3 (33.3%) with large nests. In conclusion, PAX8 can be positive in a significant proportion of nested variant of urothelial carcinoma cases, and recognition of this finding is important to avoid misdiagnosis of nested variant of urothelial carcinoma as nephrogenic adenoma based on PAX8 expression, particularly in cases with tubular differentiation and limited sampling.

The diagnosis of prostate carcinoma, especially when present in a limited amount in biopsy, is often challenging because numerous benign conditions have architectural and cytological features overlapping with and mimicking carcinoma [1]. These mimics include various anatomic structures, inflammatory and reactive conditions, and pathophysiological conditions, including atrophy, hyperplasia, and metaplasia. Many of these lesions are readily recognized and separated from malignancy but some may cause potential diagnostic difficulties. A useful approach to classifying benign mimics is based on major growth patterns of prostate carcinoma outlined in the Gleason grading system. This approach provides a conceptual framework for considering differential diagnoses. Three major growth patterns are encountered: small gland pattern mimicking Gleason score 4–6 carcinomas; large gland/cribriform growth pattern mimicking Gleason score 7–8 carcinomas; and fused glands/solid growth/single cells pattern mimicking Gleason score 8–10 carcinomas. Most benign lesions mimic small gland (acinar) adenocarcinoma.

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.

ResumoIntroduçãoO adenoma nefrogénico da bexiga (ANB) é uma variante rara e benigna dos tumores uroteliais. A literatura existente é escassa relativamente à sua etiologia, clínica e terapêutica. Este trabalho apresenta o primeiro caso descrito de um doente com infeção por vírus da imunodeficiência humana tipo 1 (VIH‐1) a quem foi diagnosticado um ANB.Caso clínicoDoente do sexo feminino, 49 anos, seropositiva para VIH‐1. Seguida em consulta por quadro clínico consistente em polaquiúria, urgência miccional, sensação de esvaziamento vesical incompleto e episódios de hematúria intermitentes. Por apresentar uma lesão vesical suspeita foi submetida a uma RTU‐V. O exame anatomopatológico foi consistente com ANB. A doente encontra‐se em regime de follow‐up tendo completado um ano sem sinais de recidiva lesional.DiscussãoO ANB é uma lesão metaplásica do urotélio. A sua etiologia não está completamente esclarecida, encontrando‐se associada a processos inflamatórios crónicos ou a um estado de imunossupressão. O seu diagnóstico é histopatológico, caracterizando‐se pela presença de estruturas tubuloglandulares semelhantes aos túbulos renais. Este trabalho assume particular relevância pelo facto de ser o primeiro caso descrito de ANB numa doente imunodeprimida por infeção com VIH‐1.AbstractIntroductionNephrogenic adenoma of the urinary bladder (NAB) is a rare and benign urothelial tumor. The existing literature is scarce regarding its etiology, clinical symptoms and therapeutic options. This paper presents the first reported case of a patient with HIV‐1 infection to whom an NAB was diagnosed.Case ReportWe report a case of a female patient of 49 years old, seropositive for HIV‐1, with pollakiuria, mictional urgency, feeling of incomplete bladder emptying and intermittent macroscopic hematuria. The patient was submitted to TURB of a suspected intravesical lesion. Histopathological examination of the resected material was consistent with an NAB. The patient is in follow‐up, having completed one year with no sign of lesion recurrence.DiscussionNAB is a metaplastic lesion of the urothelial tissue. Its etiology is not fully understood. NAB is associated with chronic inflammatory processes or to a state of immunosuppression. Its diagnosis is histological, characterized by the presence of tubular structures similar to renal tubules. This work is particularly relevant because it is the first described case of NAB in a patient immunodepressed by HIV‐1 infection.

Objectives: The aim of this study is to determine if the diagnosis of nephrogenic adenoma (NA) can be made on cytologic criteria alone and if pair box gene transcription factor 8 (PAX8) is useful in the diagnosis of NA in daily cytology practice. Methods: Cytologic features of NA previously described in a literature were used to identify NA cells in urinary specimens. Subsequently, all cytology and corresponding biopsy specimens were stained with the PAX8 immunohistochemistry stain. The stains were examined; the results were tabulated. Results: A total of 44 specimens were reviewed (35 with corresponding biopsy specimens diagnosed as NA and nine negative for NA diagnosis on corresponding biopsy specimens). Of them, 14 demonstrated features previously described as NA. None of atypical cells that were morphologically suspicious for NA showed positive staining, whereas all of the corresponding biopsy sections demonstrated nuclear PAX8 positivity. Only rare lymphocytes present in cytology specimens showed nuclear staining with PAX8. Conclusions: Assuming that the results of the PAX8 stain performed are accurate at least in most cases, as suggested by the presence of internal positive controls, our study shows that the previously described cytologic features of NA cannot be used as diagnostic criteria, since they are not characteristic for this entity.

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.

Metanephric adenoma (MA) is a rare, benign renal tumor that can be found in individuals of any age. The histological features of this lesion are well known; however, cytological features of this entity have rarely been described. Herein, we present the case of a 37-year-old white woman with multiple endocrine dysfunctions and a renal mass. The diagnosis of metanephric adenoma was suggested as a differential diagnosis during imprint cytology; this diagnosis was later confirmed by core needle biopsy (CNB) and the results of immunostaining. To our knowledge, this is the first time in the literature that the diagnosis of metanephric adenoma was initially suggested on imprint cytologic testing of a CNB. We review the literature regarding the cytologic features and immunohistochemical reactivity of this tumor to raise awareness of this entity among pathologists and to distinguish it from other lesions, such as renal-cell carcinoma, so physicians can use this information to help them avoid calling for an unnecessary radical nephrectomy.

Background.Clear cell adenocarcinoma of the urethra (CCAU) is extremely rare and a number of clinicians may be unfamiliar with its diagnosis and biological behaviour.Aims.To review the literature on CCAU.Methods.Various internet databases were used.Results/Literature Review.(i) CCAU occurs in adults and in women in the great majority of cases. (ii) It has a particular association with urethral diverticulum, which has been present in 56% of the patients; is indistinguishable from clear cell adenocarcinoma of the female genital tract but is not associated with endometriosis; and probably does not arise by malignant transformation of nephrogenic adenoma. (iii) It is usually, readily distinguished from nephrogenic adenoma because of greater cytological a-typicality and mitotic activity and does not stain for prostate-specific antigen or prostatic acid phosphatase. (iv) It has been treated by anterior exenteration in women and cystoprostatectomy in men and at times by radiotherapy; chemotherapy has rarely been given. (v) CCAU is aggressive with low 5-year survival rates. (vi) There is no consensus opinion of treatment options that would improve the prognosis.Conclusions.Few cases of CCAU have been reported. Urologists, gynaecologists, pathologists, and oncologists should report cases of CCAU they encounter and enter them into a multicentric trial to determine the best treatment options that would improve the prognosis.

Nephrogenic adenoma (NA) is a benign adenomatous lesion of the urinary tract. Long considered to be a rare phenomenon, case series from the renal transplant population suggest that it may be much more common within this group. Although NA is considered to be a lesion with low premalignant potential, hematuria, lower urinary tract symptoms, and recurrent urinary tract infections (UTIs) are frequently observed in the context of NA. Furthermore, after resection of NA, lesion recurrence and persistent symptoms are frequently observed. Here we present the case of a 69-year-old male renal transplant recipient with NA and associated recurrent UTIs despite cystoscopic resection of the primary lesion. This case is illustrative of the clinical impact of NA and the need for ongoing work into the development of strategies to manage this problematic phenomenon.

Nephrogenic adenoma is a common diagnosis in urological pathology that may be challenging for general pathologists. Due to its polymorphic appearance under the microscope, some cases can be misdiagnosed as malignancy and then unnecessarily overtreated. Aside from the typical tubules, cysts and papillae, nephrogenic adenoma may display a broad spectrum of histologic appearances and locations, some of them atypical or unexpected. These unusual and concerning features will have special consideration in this description. The goal of the review is to increase awareness of general pathologists of the varied histology of nephrogenic adenoma. Sin financiación 2.050 JCR (2019) Q3, 43/78 Pathology 0.580 SJR (2019) Q2, 86/216 Pathology and Forensic Medicine No data IDR 2019 UEM