American Urological Association - Nephrogenic Adenoma
- Epithelial proliferations along urothelial mucosa that resemble immature renal tubules.
- Associated with urothelial injury such as prior GU surgery, calculi, trauma and intravesical BCG therapy.
- Favored to represent seeding implantation and growth of displaced renal tubular cells in injured urothelial mucosa.
- Relatively common in renal transplant patients.
- Vast majority encountered in bladder and ~15% in prostatic urethra.
- Papillary and tubular growths, usually in combination (image A), (image B), (image C), & (image D).
- Monolayer of benign cuboidal to low-columnar cells and often with poke out cell nuclei (hobnail cells, image B).
- Tubules have characteristic thickened peritubular basement membrane may resemble blood vessels or, if minute, signet ring cells.
- The lumen may contain basophilic or eosinophilic secretions.
- Immunohistochemistry: PAX-2+ and S100-A1+.
- Benign outcome.
- Papillary urothelial neoplasia: multilayered, with atypia, and is p63+.
- Prostatic carcinoma: NA tubules in prostatic urethra may resemble and similarly express AMACR!; NA is PSA- or PSAP-.