KRT20 and neoplasm: Immunohistochemical staining showed the tumour cells were diffusely positive for cytokeratin 20 (CK20) (Fig. 3C) and caudal-related homeobox transcription factor 2 (CDX2) (Fig. 3D) while cytokeratin 7 (CK7), Wilms tumour 1 (WT1) and tumour protein 63 (p63) were all negative.