KRT20 and neoplasm: Immunohistochemical (IHC) staining was performed using thyroid transcription factor-1 (TTF-1), paired box protein 8 (PAX8), cytokeratin 20 (CK20), caudal-related homeobox transcription factor-2 (CDX-2) and villi protein (Villin) in order to clarify the origin of the tumor.