MUC2 and carcinoma: The pathology specimen, however, demonstrated poorly differentiated squamous cell carcinoma without metastasis to the colonic lymph nodes, and immunohistochemistry showed that the carcinoma cells were negative for CDX2, cytokeratin20 (CK20), MUC2 and MUC5AC (Figure 5), thus indicating that the carcinoma was not colorectal carcinoma [12-14].