To better understand the genetic ontogeny of inverted papilloma of urinary bladder, we analyzed telomerase reverse transcriptase (TERT) promoter mutation status in a group of 26 inverted papillomas in comparison with the mutation status of urothelial carcinoma with inverted growth (26 cases), conventional urothelial carcinoma (36 Ta noninvasive urothelial carcinoma, 35 T2 invasive urothelial carcinoma), and cystitis glandularis (25 cases).