Nephrogenic adenoma after urethral reconstruction using bladder mucosa: Report of 6 cases and review of the literature

Purpose: To our knowledge nephrogenic adenoma, an unusual benign metaplastic lesion of the urothelium, has not been reported previously following urethral reconstruction using bladder mucosa. Histopathological features, etiological factors and clinical features are discussed. Materials and Methods: We reviewed the records of 117 patients who underwent hypospadias repair with free grafts of bladder mucosa from 1982 to 1995. Results: Five children 6 to 11 years old and a 39-year-old man had nephrogenic adenoma of the urethra. Hematuria or dysuria was the usual reason for presentation. The lesions were located at the site of anastomosis between the graft and proximal urethra in 3 cases and the distal graft in 2, and they involved the whole graft in 1. Successful treatment consisted of endoscopic resection of the polyps in 4 patients, while open surgical correction was performed in 2, requiring complete excision of the previous graft in 1 and segmental resection in 1. Conclusions: The gross appearance of the lesion may be confused with that of transitional cell carcinoma or clear cell adenocarcinoma of the urethra, necessitating biopsy to rule out malignancy. Endoscopic management is possible for small tumors, although severe nephrogenic adenoma involving most of the reconstructed urethra may require complete resection of the graft and creation of a new urethra.