Inverted Papilloma•Rare, ~1% of urothelial neoplasms seen over a wide age range
•Cystoscopy shows small (<3 cm) solitary sessile lesion or may have a short stalk.
◦Urothelium invaginates into lamina propria (inverted).
◦Characterized by cords or trabeculae with peripheral palisading of basal cells and central streaming cells.
◦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%).