Home Education AUAUniversity Education Products & Resources Pathology for Urologists Urinary Bladder Non-Neoplastic Lesions Nephrogenic Adenoma

Nephrogenic Adenoma

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Image B

  • 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.

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  • Histology:
    • 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.
  • DDX:
    • 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-.