Inverted Urothelial Papilloma : Microscopic Features
Section Editor: Dharam M. Ramnani, MD
Virginia Urology, Richmond, VA, USA
Image Description
Microscopic Features: The branching and anastomosing cords and trabeculae of inverted urothelial papillomas are uniform with an orderly arrangement. They are composed of 5-10 layers of cytologically bland urothelial cells. Due to the inverted growth into the lamina propria, the trabeculae are lined peripherally by darker, basal cells whereas the center of the trabeculae shows ovoid or spindled cells streaming parallel to the cords. Mitotic activity is not increased. The trabeculae are separated by scant amount of loose fibrovascular stroma lacking inflammation.