Vesical nephrogenic adenoma: an unusual presentation of a bladder tumour

Abstract

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. IntroductionVesical nephrogenic adenoma is a rare, benign entity that appears most commonly in middle-aged males. Several hundred cases have been reported worldwide.1-5 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 (BCG). Davis published the first case in the literature in 1949. 6 The term "nephrogenic adenoma" was coined in 1950 by Friedman and Kuhlenbeck, who noted the resemblance of this lesion to the renal tubule.1 Two cases of vesical nephrogenic adenoma will be presented. Case 1A 60-year-old male with a diagnosis of chronic renal failure was seen for severe voiding symptoms and hematuria. The patient was on hemodialysis and had a history of a transurethral resection of the prostate and a bladder diverticulectomy after a transurethral resection of bladder neck. An ultrasound scan revealed a raised intra-vesical lesion. Cystoscopy showed multiple trabeculae and diverticulae of the bladder and, in the left side, a superficial papillary lesion 3 cm in diameter, which was resected. The histological study showed the presence of focal ducts lined with cuboidal epithelium without atypia, located in areas of urothelial denudation ( Fig. 1), findings compatible with vesical nephrogenic adenoma. Currently, the patient is asymptomatic, undergoes regular check-ups and is waiting for a kidney transplant due to end-stage renal disease. Case 2An 80-year-old male was seen for a consultation for hematuria. The patient had a history of two previous transurethral resections for a bladder tumour and benign prostatic hyperplasia. An ultrasound revealed a small lesion on the right side. Cystoscopy showed a 1-cm lesion in the perimeatic area, which was resected. The histological study showed encysted tubular structures lined with flattened cuboidal cells, consistent with vesical nephrogenic adenoma (Fig. 2). The patient is currently being monitored, and his condition is well-controlled. DiscussionNephrogenic adenoma (or papillary tubular adenoma) is a rare, benign metaplastic lesion.3 Its most characteristic location is in the bladder, especially in the trigone, but it is also found, to a lesser extent, in the urethra and ureters. Chronic bladder irritation by foreign bodies, trauma, urological surgery, prolonged instrumentation of the urinary...