Nephrogenic metaplasia of the bladder in renal transplant recipients. Case report.

Nephrogenic metaplasia in two cases of renal transplant recipients, following immunosuppressive treatment is reported. The lesion is rare with unknown pathogenesis. Histologically the tumor consists of cystic and tubular structures resembling the distal parts of the nephron, but may occur in any part of the urothelium lined organs from calyxes to urethra. Watchful waiting is the treatment of choice in the absence of microscopically malignant changes.