Inverted Urothelial Papilloma : Microscopic Features

With the exception of inverted urothelial papilloma, the 5th edition (2022) of WHO bluebook does not list inverted urothelial neoplasms separately, but acknowledges them within the respective sections of exophytic urothelial neoplasms. In 2012, The International Consultation on Urologic Disease/European Association of Urology recommended that the 2004 WHO/ISUP terminology for exophytic urothelial neoplasms be extrapolated to urothelial neoplasms with a predominant inverted growth pattern. Accordingly, they recognized the following:

• Inverted Urothelial Papilloma
• Inverted Papillary Urothelial Neoplasm of LMP
• Inverted Papillary Urothelial Carcinoma, Low-Grade
• Inverted Papillary Urothelial Carcinoma, High-Grade, Non-Invasive
• Inverted Papillary Urothelial Carcinoma, High-Grade, Invasive