American Urological Association - Inverted Papilloma


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Inverted Papilloma

Image A

Image B

  • Rare, ~1% of urothelial neoplasms seen over a wide age range (1st to 8th decade).
  • Cystoscopy shows small (<3 cm) solitary sessile lesion or may have a short stalk.
  • Histology:
    • Urothelium invaginates into lamina propria (inverted).
    • Characterized by cords or trabeculae with peripheral palisading of basal cells and central streaming cells (image A) & (image B).
    • Cords should be thin (a must, to distinguish from higher grade inverted urothelial neoplasms).
    • Bland cytology, but may have scattered degenerative atypia.
  • Negligible recurrence rate (<1%).