A case series of nephrogenic adenoma of the urethra and bladder in children: review of this rare diagnosis, its natural history and management, with reference to the literature

10-Year observation of a rare presentation of pure fibromyxoid nephrogenic adenoma in the renal pelvis

Nephrogenic adenoma (NA) is an unusual benign epithelial tumor in the genitourinary tract. Here we report a fibromyxoid nephrogenic adenoma in a 37-year-old female presenting with over 10-year slow-growing renal pelvic mass that was diagnosed with bland spindle cell lesion in multiple previous biopsies. This is the first reported case of pure fibromyxoid NA in renal pelvis with close comparison and correlation of biopsy and resection findings over a 10-year span. This will enhance awareness of pathologists to consider this unusual entity when examining spindle cell lesions in this setting, and prevent misdiagnosis and overtreatment of a typically benign process.

Bladder nephrogenic adenoma as a complication of surgical correction of megaureter

Background

Bladder nephrogenic adenoma (BNA) is a rare benign proliferative pathology of its mucosa. The etiopathogenesis of the disease remains uncertain, and the treatment is still challenging.

Case presentation

In this article, we present a clinical case of bladder nephrogenic adenoma in a 6-year-old boy. Clinical symptoms of the disease appeared 3 years after surgical treatment of obstructive megaureter. Histopathological and immunohistochemical examination of glandular polyp biopsies allowed excluding the tumor process and making a diagnosis.

Conclusion

Nephrogenic adenomas demonstrate a variety of morphologic patterns that may occasionally be confused with malignant processes. We described the endoscopic characteristics of BNA and characterized its histological and immunohistochemical features in a boy after ureteroneocystostomy.

Nephrogenic adenoma of the ureter in a teenager with history of leukemia

Nephrogenic adenomas represent a suspected metaplastic response of the uroepithelium to chronic inflammation and are typically associated with recurrent urinary tract infections, stones, prior radiation therapy and other irritative factors, more commonly seen in adults. Nephrogenic adenoma (also known as nephrogenic metaplasia) usually involves the bladder in adults and represents a rare lesion that can easily be misdiagnosed as a malignancy. We present the case of a 14-year-old male with prior history of acute lymphoblastic leukemia (ALL) who presented with a several month history of vague flank pain which increased in intensity, leading to an emergency department presentation with the only significant finding on exam being microhematuria. Subsequent imaging showed a tumor like replacement of the right ureter with proximal hydronephrosis, initially felt to represent recurrent leukemia. Pathology revealed the tumor like ureteral replacement to represent a nephrogenic adenoma, a benign entity which often responds to conservative management, though not previously reported in the ureter in pediatrics.

Tumour-like lesions of the urinary bladder

There are a number of benign epithelial proliferations in the bladder that may be difficult to distinguish from carcinomas, including urothelial carcinoma and its variants, squamous cell carcinoma and adenocarcinoma. If misdiagnosed, there is the potential for over treatment, with its attendant risk of complications, as well as errors relating to prognostic assessment. In the case of the misdiagnosis of high grade proliferative lesions that mimic invasive carcinoma, unnecessary radical surgery, chemotherapy and radiotherapy may result. Similarly, the misdiagnosis of lesions that have the appearance of low grade carcinoma can prompt a lifetime of radiological investigation and cystoscopies. In this review, we discuss a variety of entities that may be diagnostically challenging and emphasise the importance of identifying key morphological features that have diagnostic utility. We also highlight the importance of relevant clinical information and the clinical settings in which these lesions may occur. In this review we have divided the lesions on the basis of morphology in order to facilitate discussion relating to the differential diagnosis. The architectural patterns we discuss include papillary lesions (polypoid/papillary cystitis and papillary urothelial hyperplasia), pseudocarcinomatous proliferations (pseudocarcinomatous urothelial hyperplasia, florid proliferation of von Brunn nests and fibroepithelial polyps), glandular lesions (intestinal metaplasia and müllerianosis) and lesions with several different patterns (prostatic type urethral polyps and nephrogenic adenoma or metaplasia).

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.

Nephrogenic Adenoma: Clinical Features, Management, and Diagnostic Pitfalls

OBJECTIVE

To review the diagnosis and management of nephrogenic adenoma (NA), an uncommon benign lesion found in the urinary tract. This lesion arises from a proliferation of implanted renal tubular cells. Although more common in adults, it can occur in all ages. NAs can recur and cause significant morbidity in patients. NAs are also a potential diagnostic pitfall as they can clinically and histologically mimic malignancy in the urinary tract.

MATERIALS AND METHODS

We performed an Institutional Board Review approved search of our surgical pathology database from 2005 to 2015 for cases of NA. A retrospective chart review was performed with a focus on the clinical, pathologic, and radiographic findings in these patients.

RESULTS

We identified 32 cases of NA in 31 patients. Lesions were most common in Caucasian males (male-to-female ratio of 2:1) with an average age at diagnosis of 55 years (range 25-77). Bladder was the most common site of occurrence (81.2%), followed by ureter (9.4%), urethra (6.3%), and intrarenal collecting system (3.1%). Most patients (72%) were symptomatic and presented with hematuria (41%), lower urinary tract symptoms (28%), pelvic or flank pain (6%), hydronephrosis (19%), or urinary incontinence (13%). NA was asymptomatic and identified incidentally in 9 (28%) patients. One patient (3%) had a renal transplant and 8 (26%) patients had diabetes mellitus. Twenty-six (84%) patients were managed with endoscopic resection of their tumors.

CONCLUSION

NAs are benign lesions that may cause significant morbidity and mimic malignant tumors. There should be increased suspicion in patients with predisposing factors.

Nephrogenic Adenoma of the Urinary Bladder: A Review of the Literature

Background. Nephrogenic adenoma of the urinary bladder (NAUB) is a rare lesion associated with nonspecific symptoms and could inadvertently be misdiagnosed. Aim. To review the literature. Methods. Various internet search engines were used. Results. NAUB is a benign tubular and papillary lesion of the bladder, is more common in men and adults, and has been associated with chronic inflammation/irritation, previous bladder surgery, diverticula, renal transplantation, and intravesical BCG; recurrences and malignant transformations have been reported. Differential diagnoses include clear cell adenocarcinoma, endocervicosis, papillary urothelial carcinoma, prostatic adenocarcinoma of bladder, and nested variant of urothelial carcinoma; most NAUBs have both surface papillary and submucosal tubular components; both the papillae and tubules tend to be lined by a single layer of mitotically inactive bland cells which have pale to clear cytoplasm. Diagnosis may be established by using immunohistochemistry (positive staining with racemase; PAX2; keratins stain positive with fibromyxoid variant), electron microscopy, DNA analysis, and cytological studies. Treatment. Endoscopic resection is the treatment but recurrences including sporadic malignant transformation have been reported. Conclusions. There is no consensus on best treatment. A multicentre study is required to identify the treatment that would reduce the recurrence rate, taking into consideration that intravesical BCG is associated with NAUB.

Multifocal nephrogenic adenoma – a mimicker of malignancy

The authors report a multifocal nephrogenic adenoma of urinary bladder in an 11-y-old girl. Nephrogenic adenomas occur almost exclusively in the urinary bladder in children and are rarely multifocal. Less than 30 cases of nephrogenic adenomas have been reported in children and very few of these are multifocal. This report aims at drawing attention to this rare entity in children.

Vesical nephrogenic adenoma: an unusual presentation of a bladder tumour

Vesical nephrogenic adenoma is a rare, benign entity that appears most commonly in middle-aged males. Its etiology is unknown, but it has been linked to chronic irritating factors, such as infection, trauma, urological surgery, kidney stones, foreign bodies and chemical agents, such as Bacille Calmette-Guerin. We report 2 new cases with a history of transurethral resection of the bladder and the prostate and a history of prolonged voiding symptoms. In both cases, the findings of encysted tubular structures lined with flattened cuboidal cells without atypia were consistent with the diagnosis of vesical nephrogenic adenoma.

Eosinophilic cystitis and nephrogenic adenoma of the bladder: a rare association of 2 unusual findings in childhood

Neither eosinophilic cystitis nor nephrogenic adenoma is often diagnosed in children, with few pediatric cases being reported in the literature. Although these maladies share the same predisposing conditions, namely, chronic irritation or injury to the urothelium and lower urinary tract and symptoms such as dysuria, hematuria, and urinary frequency, their concomitance is exceptional. Herein, we report the case of an 8-year-old boy with a previous history of bladder surgery presenting histologically diagnosed eosinophilic cystitis and nephrogenic adenoma.