Nephrogenic adenoma of the urinary bladder: a report of three cases and a review of the literature.

BACKGROUND: Nephrogenic adenoma (NA) is a rare, benign disease of the urinary tract, usually as a response to chronic irritation or trauma. Its diagnosis, staging, and treatment are not well established. CASE REPORT: We report on 3 cases of nephrogenic adenoma of the urinary bladder treated in our hospital between February 2011 and December 2012 to assess our experience and clinical outcome updating and reviewing the literature concerning this issue. All patients had undergone previous open urosurgery. Two patients had kidney transplantation. Gross hematuria and microhematuria were found in 2 patients. One patient had recurrent urinary tract infection. One patient had NA associated with transitional cell carcinoma (TCC). Recurrent nephrogenic adenomas were diagnosed in 2 patients (time to disease relapse was 5 and 9 months). All nephrogenic adenomas and recurrent tumors were treated with transurethral resection. CONCLUSIONS: Although NA is a benign metaplastic lesion of the urothelium, its recurrence rate is relatively high, thus careful and regular follow-up is necessary. Endoscopic characteristics of NA are not specific and a definite diagnosis must be made after histological analysis of resected specimens.