CDX2 and carcinoma: The typical immunophenotypic profile of lower GI tract (colorectal or appendiceal) carcinomas is cytokeratin (CK)7−/CK20+/caudal-type homeobox 2 (CDX2)+, whereas about 60% of SBAs have been reported to co-express CK7 and CK20 and around 50% of SBAs are negative for CDX2 [11,12,13].