CDX2 and urothelial carcinoma: Immunohistochemistry (IHC) results revealed bladder biopsy with a high-grade muscle invasive urothelial carcinoma with areas of conventional and signet ring cell morphology: GATA 3 positive diffuse in tumor cells, CK 20 focal positive in tumor cells, CK5/6, P63 and CDX2 negative in tumor cells; rectal wall biopsy with same characteristics for tumor cells but with positive internal control markers for CK 20, CDX2 in colonic epithelium(Figure 4A–F).