PAX8 and neoplasm: Immunohistochemical stains were positive for PAX8, AE1/AE3, E-cadherin, CD10, and vimentin; the tumor was negative for CK7, CD117, racemase, ALK, and HMB45; the tumor showed focal, scattered staining for Melan-A and very weak cytoplasmic staining for CAIX.