Bulky transitional cell carcinoma of bladder with inverted proliferation

Two women, aged 51 and 62 years, had unusual transitional cell carcinomas of the urinary bladder which were > 5 cm and had a structural resemblance to inverted papilloma or Brunn's nest. They were treated by bladder-preserving surgery with no evidence of recurrence after 30 and 103 months follow-up, respectively. Our cases show some hitherto unrecognized aspects of transitional cell carcinoma with inverted proliferation because the tumors are usually found in males and tend to be aggressive.