Nephrogenic adenoma of the bladder: two case reports and literature review

In the two cases we report here, tumors were diagnosed as nephrogenic adenoma by pathohistological examination. Case 1 was a 72-year-old female presenting with a bladder tumor 8 months after receiving ureteral tumor surgery. Transurethral resection of bladder tumor (TUR-Bt) was performed. Case 2 was a 57-year-old female who had received intravesical bacillus Calmette-Guérin (BCG) treatment 6 times after her fifth TUR-Bt. Two tumors were found by cystoscopy, and TUR-Bt was performed. There have been 39 cases of nephrogenic adenoma of the bladder reported in Japan; 21 were male and 18 female with a mean age of 56.5 years. The main complaint was hematuria, which was seen in 16 cases followed by pollakisuria in 6 cases. Nephrogenic adenoma occurred after surgery of the urinary tract in 16 cases, followed by urinary tract infection in 9 cases and intravesical BCG treatment in 6 cases. The ratio of cases occurring after intravesical BCG treatment has increased since BCG approval for bladder carcinoma treatment in December 1996 in Japan, and an increase in the number of cases is expected in the future.