Nephrogenic adenomas of the urinary system: a clinicopathologic analysis of 30 cases

Objective: Nephrogenic adenomas (NA) are benign lesions that may occur in several sites throughout the urinary tract, from the renal pelvis to urethra, and especially in the bladder. They are strongly associated with urinary tract irritation, chronic inflammation, previous urologic surgery, and intravesical instrumentations. Our study aims to evaluate and present the clinicopathologic characteristics and findings of cases that were diagnosed with nephrogenic adenoma accompanied by relevant information from the literature. Material and Methods: Our study includes 30 patients who were pathologically diagnosed with NA from February 2005 to November 2017. Results: Among these patients, 63.3% were males and mean age was 60 years. The most common site of occurrence was the bladder (86.6%), followed by the ureter (6.7%) and the urethra (6.7%). Most patients presented with hematuria (36.7%). History of concurrent bladder cancer was present in 26.7% of patients, but there were no cases of de novo bladder cancer diagnosed after NA. Recurrence of NA after initial resection occurred in only 10% of patients who underwent follow-up cystoscopy. Nephrogenic adenoma is a rare lesion associated with nonspecific symptoms and endoscopic features. Definite diagnosis must be made after histological analysis of resected specimens. Conclusion: Nephrogenic adenoma is a rare lesion associated with nonspecific symptoms and nonspesific endoscopic features. A definite diagnosis must be after histological analysis of resected specimens. Keywords: nephrogenic adenoma, urothelial lesion, bladder, ureter

Mimickers of Urothelial Carcinoma and the Approach to Differential Diagnosis

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.

Simulators of Urothelial Carcinoma

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 and inverted), nephrogenic adenoma, polypoid cystitis, fibroepithelial polyp, prostatic-type polyp, verumontanum cyst, xanthogranulomatous inflammation, reactive changes secondary to BCG instillations, schistosomiasis, keratinizing desquamative squamous metaplasia, post-radiation changes, vaginal-type metaplasia, endocervicosis/endometriosis (müllerianosis), malakoplakia, florid von Brunn nest proliferation, cystitis/ureteritis cystica and glandularis, among others, still other cellular proliferations with concerning histological features and poorly understood etiopathogenesis like IgG4-related disease, PEComa, and pseudosarcomatous myofibroblastic proliferations (post-operative spindle cell nodule, inflammatory myofibroblastic tumor), 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.

Nephrogenic Adenoma of the Urinary Bladder after Kidney Transplantation: Long-Term Follow-Up

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.