PAX8 and urothelial carcinoma: Pathology: high-grade urothelial carcinoma. IHC: 34βE12 (+), CK7 (+), p63 (rare+), CK20 (focal+), GATA3 (−), RCC antigen (−) with focal/partial CAIX and CD10, PAX8 (+). HER2 overexpression (IHC 3+).