CK20 expression was significantly lower in IUP (Fig 3C), for which 2 of 36 cases (5.6%) were positive, than in LGNUC with an inverted growth pattern (Fig 3D), for which 14 of 38 cases (36.8%) were positive (P = 0.001). This evidence concerns the gene KRT20 and inverted urothelial papilloma.