[Nephrogenic adenoma--benign lesion of urinary tract system]

Nephrogenic adenoma is a rare metaplastic benign lesion of the urinary tract caused by chronic irritation to the urinary epithelium. The appearance of this lesion is usually characterized by hematuria and irritative symptoms. Nephrogenic adenoma may be found most commonly in the bladder and the urethra and less frequently in the renal pelvis and ureters. We present 5 patients who underwent surgery due to bladder or urethral nephrogenic adenoma. Despite the fact that nephrogenic adenoma is a benign lesion, long term follow-up is needed due to the high recurrence rate and the potential, though rare, malignant transformation.